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1. Array Class
2. Enum Class
3. GC Class
   
4. Enumerable Class
5. IEnumerable<T> Interface

Array Class

https://msdn.microsoft.com/en-us/library/system.array.aspx

Provides methods for creating, manipulating, searching, and sorting arrays, thereby serving as the base class for all arrays in the common language runtime.

To browse the .NET Framework source code for this type, see the Reference Source.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

Inheritance Hierarchy

System.Object
  System.Array

Syntax

C#

C++

F#

VB

[SerializableAttribute]
[ComVisibleAttribute(true)]
public abstract class Array : ICloneable, IList, ICollection, 
	IEnumerable, IStructuralComparable, IStructuralEquatable

Properties

	Name	Description
	IsFixedSize	Gets a value indicating whether the Array has a fixed size.
	IsReadOnly	Gets a value indicating whether the Array is read-only.
	IsSynchronized	Gets a value indicating whether access to the Array is synchronized (thread safe).
	Length	Gets the total number of elements in all the dimensions of the Array.
	LongLength	Gets a 64-bit integer that represents the total number of elements in all the dimensions of the Array.
	Rank	Gets the rank (number of dimensions) of the Array. For example, a one-dimensional array returns 1, a two-dimensional array returns 2, and so on.
	SyncRoot	Gets an object that can be used to synchronize access to the Array.

Methods

	Name	Description
	AsReadOnly<T>(T[])	Returns a read-only wrapper for the specified array.
	BinarySearch(Array, Int32, Int32, Object)	Searches a range of elements in a one-dimensional sorted array for a value, using the IComparable interface implemented by each element of the array and by the specified value.
	BinarySearch(Array, Int32, Int32, Object, IComparer)	Searches a range of elements in a one-dimensional sorted array for a value, using the specified IComparer interface.
	BinarySearch(Array, Object)	Searches an entire one-dimensional sorted array for a specific element, using the IComparable interface implemented by each element of the array and by the specified object.
	BinarySearch(Array, Object, IComparer)	Searches an entire one-dimensional sorted array for a value using the specified IComparer interface.
	BinarySearch<T>(T[], T)	Searches an entire one-dimensional sorted array for a specific element, using the IComparable<T> generic interface implemented by each element of the Array and by the specified object.
	BinarySearch<T>(T[], T, IComparer<T>)	Searches an entire one-dimensional sorted array for a value using the specified IComparer<T> generic interface.
	BinarySearch<T>(T[], Int32, Int32, T)	Searches a range of elements in a one-dimensional sorted array for a value, using the IComparable<T> generic interface implemented by each element of the Array and by the specified value.
	BinarySearch<T>(T[], Int32, Int32, T, IComparer<T>)	Searches a range of elements in a one-dimensional sorted array for a value, using the specified IComparer<T> generic interface.
	Clear(Array, Int32, Int32)	Sets a range of elements in an array to the default value of each element type.
	Clone()	Creates a shallow copy of the Array.
	ConstrainedCopy(Array, Int32, Array, Int32, Int32)	Copies a range of elements from an Array starting at the specified source index and pastes them to another Array starting at the specified destination index. Guarantees that all changes are undone if the copy does not succeed completely.
	ConvertAll<TInput, TOutput>(TInput[], Converter<TInput, TOutput>)	Converts an array of one type to an array of another type.
	Copy(Array, Array, Int32)	Copies a range of elements from an Array starting at the first element and pastes them into another Array starting at the first element. The length is specified as a 32-bit integer.
	Copy(Array, Array, Int64)	Copies a range of elements from an Array starting at the first element and pastes them into another Array starting at the first element. The length is specified as a 64-bit integer.
	Copy(Array, Int32, Array, Int32, Int32)	Copies a range of elements from an Array starting at the specified source index and pastes them to another Array starting at the specified destination index. The length and the indexes are specified as 32-bit integers.
	Copy(Array, Int64, Array, Int64, Int64)	Copies a range of elements from an Array starting at the specified source index and pastes them to another Array starting at the specified destination index. The length and the indexes are specified as 64-bit integers.
	CopyTo(Array, Int32)	Copies all the elements of the current one-dimensional array to the specified one-dimensional array starting at the specified destination array index. The index is specified as a 32-bit integer.
	CopyTo(Array, Int64)	Copies all the elements of the current one-dimensional array to the specified one-dimensional array starting at the specified destination array index. The index is specified as a 64-bit integer.
	CreateInstance(Type, Int32)	Creates a one-dimensional Array of the specified Type and length, with zero-based indexing.
	CreateInstance(Type, Int32, Int32)	Creates a two-dimensional Array of the specified Type and dimension lengths, with zero-based indexing.
	CreateInstance(Type, Int32, Int32, Int32)	Creates a three-dimensional Array of the specified Type and dimension lengths, with zero-based indexing.
	CreateInstance(Type, Int32[])	Creates a multidimensional Array of the specified Type and dimension lengths, with zero-based indexing. The dimension lengths are specified in an array of 32-bit integers.
	CreateInstance(Type, Int32[], Int32[])	Creates a multidimensional Array of the specified Type and dimension lengths, with the specified lower bounds.
	CreateInstance(Type, Int64[])	Creates a multidimensional Array of the specified Type and dimension lengths, with zero-based indexing. The dimension lengths are specified in an array of 64-bit integers.
	Empty<T>()	Returns an empty array.
	Equals(Object)	Determines whether the specified object is equal to the current object.(Inherited from Object.)
	Exists<T>(T[], Predicate<T>)	Determines whether the specified array contains elements that match the conditions defined by the specified predicate.
	Finalize()	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)
	Find<T>(T[], Predicate<T>)	Searches for an element that matches the conditions defined by the specified predicate, and returns the first occurrence within the entire Array.
	FindAll<T>(T[], Predicate<T>)	Retrieves all the elements that match the conditions defined by the specified predicate.
	FindIndex<T>(T[], Int32, Int32, Predicate<T>)	Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the Array that starts at the specified index and contains the specified number of elements.
	FindIndex<T>(T[], Int32, Predicate<T>)	Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the range of elements in the Array that extends from the specified index to the last element.
	FindIndex<T>(T[], Predicate<T>)	Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the first occurrence within the entire Array.
	FindLast<T>(T[], Predicate<T>)	Searches for an element that matches the conditions defined by the specified predicate, and returns the last occurrence within the entire Array.
	FindLastIndex<T>(T[], Int32, Int32, Predicate<T>)	Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the range of elements in the Array that contains the specified number of elements and ends at the specified index.
	FindLastIndex<T>(T[], Int32, Predicate<T>)	Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the range of elements in the Array that extends from the first element to the specified index.
	FindLastIndex<T>(T[], Predicate<T>)	Searches for an element that matches the conditions defined by the specified predicate, and returns the zero-based index of the last occurrence within the entire Array.
	ForEach<T>(T[], Action<T>)	Performs the specified action on each element of the specified array.
	GetEnumerator()	Returns an IEnumerator for the Array.
	GetHashCode()	Serves as the default hash function. (Inherited from Object.)
	GetLength(Int32)	Gets a 32-bit integer that represents the number of elements in the specified dimension of the Array.
	GetLongLength(Int32)	Gets a 64-bit integer that represents the number of elements in the specified dimension of the Array.
	GetLowerBound(Int32)	Gets the index of the first element of the specified dimension in the array.
	GetType()	Gets the Type of the current instance.(Inherited from Object.)
	GetUpperBound(Int32)	Gets the index of the last element of the specified dimension in the array.
	GetValue(Int32)	Gets the value at the specified position in the one-dimensional Array. The index is specified as a 32-bit integer.
	GetValue(Int32, Int32)	Gets the value at the specified position in the two-dimensional Array. The indexes are specified as 32-bit integers.
	GetValue(Int32, Int32, Int32)	Gets the value at the specified position in the three-dimensional Array. The indexes are specified as 32-bit integers.
	GetValue(Int32[])	Gets the value at the specified position in the multidimensional Array. The indexes are specified as an array of 32-bit integers.
	GetValue(Int64)	Gets the value at the specified position in the one-dimensional Array. The index is specified as a 64-bit integer.
	GetValue(Int64, Int64)	Gets the value at the specified position in the two-dimensional Array. The indexes are specified as 64-bit integers.
	GetValue(Int64, Int64, Int64)	Gets the value at the specified position in the three-dimensional Array. The indexes are specified as 64-bit integers.
	GetValue(Int64[])	Gets the value at the specified position in the multidimensional Array. The indexes are specified as an array of 64-bit integers.
	IndexOf(Array, Object)	Searches for the specified object and returns the index of its first occurrence in a one-dimensional array.
	IndexOf(Array, Object, Int32)	Searches for the specified object in a range of elements of a one-dimensional array, and returns the index of its first occurrence. The range extends from a specified index to the end of the array.
	IndexOf(Array, Object, Int32, Int32)	Searches for the specified object in a range of elements of a one-dimensional array, and returns the index of ifs first occurrence. The range extends from a specified index for a specified number of elements.
	IndexOf<T>(T[], T)	Searches for the specified object and returns the index of its first occurrence in a one-dimensional array.
	IndexOf<T>(T[], T, Int32)	Searches for the specified object in a range of elements of a one dimensional array, and returns the index of its first occurrence. The range extends from a specified index to the end of the array.
	IndexOf<T>(T[], T, Int32, Int32)	Searches for the specified object in a range of elements of a one-dimensional array, and returns the index of its first occurrence. The range extends from a specified index for a specified number of elements.
	Initialize()	Initializes every element of the value-type Array by calling the default constructor of the value type.
	LastIndexOf(Array, Object)	Searches for the specified object and returns the index of the last occurrence within the entire one-dimensional Array.
	LastIndexOf(Array, Object, Int32)	Searches for the specified object and returns the index of the last occurrence within the range of elements in the one-dimensional Array that extends from the first element to the specified index.
	LastIndexOf(Array, Object, Int32, Int32)	Searches for the specified object and returns the index of the last occurrence within the range of elements in the one-dimensional Array that contains the specified number of elements and ends at the specified index.
	LastIndexOf<T>(T[], T)	Searches for the specified object and returns the index of the last occurrence within the entire Array.
	LastIndexOf<T>(T[], T, Int32)	Searches for the specified object and returns the index of the last occurrence within the range of elements in the Array that extends from the first element to the specified index.
	LastIndexOf<T>(T[], T, Int32, Int32)	Searches for the specified object and returns the index of the last occurrence within the range of elements in the Array that contains the specified number of elements and ends at the specified index.
	MemberwiseClone()	Creates a shallow copy of the current Object.(Inherited from Object.)
	Resize<T>(T[], Int32)	Changes the number of elements of a one-dimensional array to the specified new size.
	Reverse(Array)	Reverses the sequence of the elements in the entire one-dimensional Array.
	Reverse(Array, Int32, Int32)	Reverses the sequence of the elements in a range of elements in the one-dimensional Array.
	SetValue(Object, Int32)	Sets a value to the element at the specified position in the one-dimensional Array. The index is specified as a 32-bit integer.
	SetValue(Object, Int32, Int32)	Sets a value to the element at the specified position in the two-dimensional Array. The indexes are specified as 32-bit integers.
	SetValue(Object, Int32, Int32, Int32)	Sets a value to the element at the specified position in the three-dimensional Array. The indexes are specified as 32-bit integers.
	SetValue(Object, Int32[])	Sets a value to the element at the specified position in the multidimensional Array. The indexes are specified as an array of 32-bit integers.
	SetValue(Object, Int64)	Sets a value to the element at the specified position in the one-dimensional Array. The index is specified as a 64-bit integer.
	SetValue(Object, Int64, Int64)	Sets a value to the element at the specified position in the two-dimensional Array. The indexes are specified as 64-bit integers.
	SetValue(Object, Int64, Int64, Int64)	Sets a value to the element at the specified position in the three-dimensional Array. The indexes are specified as 64-bit integers.
	SetValue(Object, Int64[])	Sets a value to the element at the specified position in the multidimensional Array. The indexes are specified as an array of 64-bit integers.
	Sort(Array)	Sorts the elements in an entire one-dimensional Array using the IComparable implementation of each element of the Array.
	Sort(Array, Array)	Sorts a pair of one-dimensional Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the IComparable implementation of each key.
	Sort(Array, Array, IComparer)	Sorts a pair of one-dimensional Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the specified IComparer.
	Sort(Array, Array, Int32, Int32)	Sorts a range of elements in a pair of one-dimensional Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the IComparable implementation of each key.
	Sort(Array, Array, Int32, Int32, IComparer)	Sorts a range of elements in a pair of one-dimensional Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the specified IComparer.
	Sort(Array, IComparer)	Sorts the elements in a one-dimensional Array using the specified IComparer.
	Sort(Array, Int32, Int32)	Sorts the elements in a range of elements in a one-dimensional Array using the IComparable implementation of each element of the Array.
	Sort(Array, Int32, Int32, IComparer)	Sorts the elements in a range of elements in a one-dimensional Array using the specified IComparer.
	Sort<T>(T[])	Sorts the elements in an entire Array using the IComparable<T> generic interface implementation of each element of the Array.
	Sort<T>(T[], Comparison<T>)	Sorts the elements in an Array using the specified Comparison<T>.
	Sort<T>(T[], IComparer<T>)	Sorts the elements in an Array using the specified IComparer<T> generic interface.
	Sort<T>(T[], Int32, Int32)	Sorts the elements in a range of elements in an Array using the IComparable<T> generic interface implementation of each element of the Array.
	Sort<T>(T[], Int32, Int32, IComparer<T>)	Sorts the elements in a range of elements in an Array using the specified IComparer<T> generic interface.
	Sort<TKey, TValue>(TKey[], TValue[])	Sorts a pair of Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the IComparable<T> generic interface implementation of each key.
	Sort<TKey, TValue>(TKey[], TValue[], IComparer<TKey>)	Sorts a pair of Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the specified IComparer<T> generic interface.
	Sort<TKey, TValue>(TKey[], TValue[], Int32, Int32)	Sorts a range of elements in a pair of Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the IComparable<T> generic interface implementation of each key.
	Sort<TKey, TValue>(TKey[], TValue[], Int32, Int32, IComparer<TKey>)	Sorts a range of elements in a pair of Array objects (one contains the keys and the other contains the corresponding items) based on the keys in the first Array using the specified IComparer<T> generic interface.
	ToString()	Returns a string that represents the current object.(Inherited from Object.)
	TrueForAll<T>(T[], Predicate<T>)	Determines whether every element in the array matches the conditions defined by the specified predicate.

Explicit Interface Implementations

	Name	Description
	IList.Add(Object)	Calling this method always throws a NotSupportedException exception.
	IList.Clear()	Removes all items from the IList.
	IList.Contains(Object)	Determines whether an element is in the IList.
	IList.IndexOf(Object)	Determines the index of a specific item in the IList.
	IList.Insert(Int32, Object)	Inserts an item to the IList at the specified index.
	IList.Remove(Object)	Removes the first occurrence of a specific object from the IList.
	IList.RemoveAt(Int32)	Removes the IList item at the specified index.
	IStructuralComparable.CompareTo(Object, IComparer)	Determines whether the current collection object precedes, occurs in the same position as, or follows another object in the sort order.
	IStructuralEquatable.Equals(Object, IEqualityComparer)	Determines whether an object is equal to the current instance.
	IStructuralEquatable.GetHashCode(IEqualityComparer)	Returns a hash code for the current instance.
	ICollection.Count	Gets the number of elements contained in the Array.
	IList.Item[Int32]	Gets or sets the element at the specified index.

Extension Methods

	Name	Description
	AsParallel()	Overloaded. Enables parallelization of a query.(Defined by ParallelEnumerable.)
	AsQueryable()	Overloaded. Converts an IEnumerable to an IQueryable.(Defined by Queryable.)
	Cast<TResult>()	Casts the elements of an IEnumerable to the specified type.(Defined by Enumerable.)
	OfType<TResult>()	Filters the elements of an IEnumerable based on a specified type.(Defined by Enumerable.)

Enum Class

https://msdn.microsoft.com/en-us/library/system.enum(v=vs.110).aspx

Provides the base class for enumerations.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

Inheritance Hierarchy

System.Object
  System.ValueType
    System.Enum

Syntax

C#

C++

F#

VB

[SerializableAttribute]
[ComVisibleAttribute(true)]
public abstract class Enum : ValueType, IComparable, IFormattable, 
	IConvertible

Constructors

	Name	Description
	Enum()	Initializes a new instance of the Enum class.

Methods

	Name	Description
	CompareTo(Object)	Compares this instance to a specified object and returns an indication of their relative values.
	Equals(Object)	Returns a value indicating whether this instance is equal to a specified object.(Overrides ValueType.Equals(Object).)
	Finalize()	Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)
	Format(Type, Object, String)	Converts the specified value of a specified enumerated type to its equivalent string representation according to the specified format.
	GetHashCode()	Returns the hash code for the value of this instance.(Overrides ValueType.GetHashCode().)
	GetName(Type, Object)	Retrieves the name of the constant in the specified enumeration that has the specified value.
	GetNames(Type)	Retrieves an array of the names of the constants in a specified enumeration.
	GetType()	Gets the Type of the current instance.(Inherited from Object.)
	GetTypeCode()	Returns the type code of the underlying type of this enumeration member.
	GetUnderlyingType(Type)	Returns the underlying type of the specified enumeration.
	GetValues(Type)	Retrieves an array of the values of the constants in a specified enumeration.
	HasFlag(Enum)	Determines whether one or more bit fields are set in the current instance.
	IsDefined(Type, Object)	Returns an indication whether a constant with a specified value exists in a specified enumeration.
	MemberwiseClone()	Creates a shallow copy of the current Object.(Inherited from Object.)
	Parse(Type, String)	Converts the string representation of the name or numeric value of one or more enumerated constants to an equivalent enumerated object.
	Parse(Type, String, Boolean)	Converts the string representation of the name or numeric value of one or more enumerated constants to an equivalent enumerated object. A parameter specifies whether the operation is case-insensitive.
	ToObject(Type, Byte)	Converts the specified 8-bit unsigned integer to an enumeration member.
	ToObject(Type, Int16)	Converts the specified 16-bit signed integer to an enumeration member.
	ToObject(Type, Int32)	Converts the specified 32-bit signed integer to an enumeration member.
	ToObject(Type, Int64)	Converts the specified 64-bit signed integer to an enumeration member.
	ToObject(Type, Object)	Converts the specified object with an integer value to an enumeration member.
	ToObject(Type, SByte)	Converts the specified 8-bit signed integer value to an enumeration member.
	ToObject(Type, UInt16)	Converts the specified 16-bit unsigned integer value to an enumeration member.
	ToObject(Type, UInt32)	Converts the specified 32-bit unsigned integer value to an enumeration member.
	ToObject(Type, UInt64)	Converts the specified 64-bit unsigned integer value to an enumeration member.
	ToString()	Converts the value of this instance to its equivalent string representation.(Overrides ValueType.ToString().)
	ToString(IFormatProvider)	Obsolete. This method overload is obsolete; use Enum.ToString().
	ToString(String)	Converts the value of this instance to its equivalent string representation using the specified format.
	ToString(String, IFormatProvider)	Obsolete. This method overload is obsolete; use Enum.ToString(String).
	TryParse<TEnum>(String, TEnum)	Converts the string representation of the name or numeric value of one or more enumerated constants to an equivalent enumerated object. The return value indicates whether the conversion succeeded.
	TryParse<TEnum>(String, Boolean, TEnum)	Converts the string representation of the name or numeric value of one or more enumerated constants to an equivalent enumerated object. A parameter specifies whether the operation is case-sensitive. The return value indicates whether the conversion succeeded.

Explicit Interface Implementations

	Name	Description
	IConvertible.ToBoolean(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a Boolean value based on the underlying type.
	IConvertible.ToByte(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to an 8-bit unsigned integer based on the underlying type.
	IConvertible.ToChar(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a Unicode character based on the underlying type.
	IConvertible.ToDateTime(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a DateTime based on the underlying type.
	IConvertible.ToDecimal(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a Decimal based on the underlying type.
	IConvertible.ToDouble(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a double-precision floating point number based on the underlying type.
	IConvertible.ToInt16(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a 16-bit signed integer based on the underlying type.
	IConvertible.ToInt32(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a 32-bit signed integer based on the underlying type.
	IConvertible.ToInt64(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a 64-bit signed integer based on the underlying type.
	IConvertible.ToSByte(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to an 8-bit signed integer based on the underlying type.
	IConvertible.ToSingle(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a single-precision floating-point number based on the underlying type.
	IConvertible.ToType(Type, IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a specified type based on the underlying type.
	IConvertible.ToUInt16(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a 16-bit unsigned integer based on the underlying type.
	IConvertible.ToUInt32(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a 32-bit unsigned integer based on the underlying type.
	IConvertible.ToUInt64(IFormatProvider)	This API supports the product infrastructure and is not intended to be used directly from your code. Converts the current value to a 64-bit unsigned integer based on the underlying type.

GC Class

https://msdn.microsoft.com/en-us/library/system.gc(v=vs.110).aspx

Controls the system garbage collector, a service that automatically reclaims unused memory.

Namespace:   System
Assembly:  mscorlib (in mscorlib.dll)

Inheritance Hierarchy

System.Object
  System.GC

Syntax

C#

C++

F#

VB

public static class GC

Properties

	Name	Description
	MaxGeneration	Gets the maximum number of generations that the system currently supports.

Methods

	Name	Description
	AddMemoryPressure(Int64)	Informs the runtime of a large allocation of unmanaged memory that should be taken into account when scheduling garbage collection.
	CancelFullGCNotification()	Cancels the registration of a garbage collection notification.
	Collect()	Forces an immediate garbage collection of all generations.
	Collect(Int32)	Forces an immediate garbage collection from generation 0 through a specified generation.
	Collect(Int32, GCCollectionMode)	Forces a garbage collection from generation 0 through a specified generation, at a time specified by a GCCollectionMode value.
	Collect(Int32, GCCollectionMode, Boolean)	Forces a garbage collection from generation 0 through a specified generation, at a time specified by a GCCollectionMode value, with a value specifying whether the collection should be blocking.
	Collect(Int32, GCCollectionMode, Boolean, Boolean)	Forces a garbage collection from generation 0 through a specified generation, at a time specified by a GCCollectionMode value, with values that specify whether the collection should be blocking and compacting.
	CollectionCount(Int32)	Returns the number of times garbage collection has occurred for the specified generation of objects.
	EndNoGCRegion()	Ends the no GC region latency mode.
	GetGeneration(Object)	Returns the current generation number of the specified object.
	GetGeneration(WeakReference)	Returns the current generation number of the target of a specified weak reference.
	GetTotalMemory(Boolean)	Retrieves the number of bytes currently thought to be allocated. A parameter indicates whether this method can wait a short interval before returning, to allow the system to collect garbage and finalize objects.
	KeepAlive(Object)	References the specified object, which makes it ineligible for garbage collection from the start of the current routine to the point where this method is called.
	RegisterForFullGCNotification(Int32, Int32)	Specifies that a garbage collection notification should be raised when conditions favor full garbage collection and when the collection has been completed.
	RemoveMemoryPressure(Int64)	Informs the runtime that unmanaged memory has been released and no longer needs to be taken into account when scheduling garbage collection.
	ReRegisterForFinalize(Object)	Requests that the system call the finalizer for the specified object for which SuppressFinalize has previously been called.
	SuppressFinalize(Object)	Requests that the common language runtime not call the finalizer for the specified object.
	TryStartNoGCRegion(Int64)	Attempts to disallow garbage collection during the execution of a critical path if a specified amount of memory is available.
	TryStartNoGCRegion(Int64, Boolean)	Attempts to disallow garbage collection during the execution of a critical path if a specified amount of memory is available, and controls whether the garbage collector does a full blocking garbage collection if not enough memory is initially available.
	TryStartNoGCRegion(Int64, Int64)	Attempts to disallow garbage collection during the execution of a critical path if a specified amount of memory is available for the large object heap and the small object heap.
	TryStartNoGCRegion(Int64, Int64, Boolean)	Attempts to disallow garbage collection during the execution of a critical path if a specified amount of memory is available for the large object heap and the small object heap, and controls whether the garbage collector does a full blocking garbage collection if not enough memory is initially available.
	WaitForFullGCApproach()	Returns the status of a registered notification for determining whether a full, blocking garbage collection by the common language runtime is imminent.
	WaitForFullGCApproach(Int32)	Returns, in a specified time-out period, the status of a registered notification for determining whether a full, blocking garbage collection by the common language runtime is imminent.
	WaitForFullGCComplete()	Returns the status of a registered notification for determining whether a full, blocking garbage collection by the common language runtime has completed.
	WaitForFullGCComplete(Int32)	Returns, in a specified time-out period, the status of a registered notification for determining whether a full, blocking garbage collection by common language the runtime has completed.
	WaitForPendingFinalizers()	Suspends the current thread until the thread that is processing the queue of finalizers has emptied that queue.

Enumerable Class

https://msdn.microsoft.com/en-us/library/system.linq.enumerable(v=vs.110).aspx

Provides a set of static (Shared in Visual Basic) methods for querying objects that implement IEnumerable<T>.

Namespace:   System.Linq
Assembly:  System.Core (in System.Core.dll)

Inheritance Hierarchy

System.Object
  System.Linq.Enumerable

Syntax

C#

C++

F#

VB

public static class Enumerable

Methods

	Name	Description
	Aggregate<TSource>(IEnumerable<TSource>, Func<TSource, TSource, TSource>)	Applies an accumulator function over a sequence.
	Aggregate<TSource, TAccumulate>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>)	Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value.
	Aggregate<TSource, TAccumulate, TResult>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate, TSource, TAccumulate>, Func<TAccumulate, TResult>)	Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value.
	All<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Determines whether all elements of a sequence satisfy a condition.
	Any<TSource>(IEnumerable<TSource>)	Determines whether a sequence contains any elements.
	Any<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Determines whether any element of a sequence satisfies a condition.
	AsEnumerable<TSource>(IEnumerable<TSource>)	Returns the input typed as IEnumerable<T>.
	Average(IEnumerable<Decimal>)	Computes the average of a sequence of Decimal values.
	Average(IEnumerable<Double>)	Computes the average of a sequence of Double values.
	Average(IEnumerable<Int32>)	Computes the average of a sequence of Int32 values.
	Average(IEnumerable<Int64>)	Computes the average of a sequence of Int64 values.
	Average(IEnumerable<Nullable<Decimal>>)	Computes the average of a sequence of nullable Decimal values.
	Average(IEnumerable<Nullable<Double>>)	Computes the average of a sequence of nullable Double values.
	Average(IEnumerable<Nullable<Int32>>)	Computes the average of a sequence of nullable Int32 values.
	Average(IEnumerable<Nullable<Int64>>)	Computes the average of a sequence of nullable Int64 values.
	Average(IEnumerable<Nullable<Single>>)	Computes the average of a sequence of nullable Single values.
	Average(IEnumerable<Single>)	Computes the average of a sequence of Single values.
	Average<TSource>(IEnumerable<TSource>, Func<TSource, Decimal>)	Computes the average of a sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence.
	Average<TSource>(IEnumerable<TSource>, Func<TSource, Double>)	Computes the average of a sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.
	Average<TSource>(IEnumerable<TSource>, Func<TSource, Int32>)	Computes the average of a sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence.
	Average<TSource>(IEnumerable<TSource>, Func<TSource, Int64>)	Computes the average of a sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence.
	Average<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Decimal>>)	Computes the average of a sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence.
	Average<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Double>>)	Computes the average of a sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence.
	Average<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Int32>>)	Computes the average of a sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.
	Average<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Int64>>)	Computes the average of a sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.
	Average<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Single>>)	Computes the average of a sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence.
	Average<TSource>(IEnumerable<TSource>, Func<TSource, Single>)	Computes the average of a sequence of Single values that are obtained by invoking a transform function on each element of the input sequence.
	Cast<TResult>(IEnumerable)	Casts the elements of an IEnumerable to the specified type.
	Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)	Concatenates two sequences.
	Contains<TSource>(IEnumerable<TSource>, TSource)	Determines whether a sequence contains a specified element by using the default equality comparer.
	Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>)	Determines whether a sequence contains a specified element by using a specified IEqualityComparer<T>.
	Count<TSource>(IEnumerable<TSource>)	Returns the number of elements in a sequence.
	Count<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Returns a number that represents how many elements in the specified sequence satisfy a condition.
	DefaultIfEmpty<TSource>(IEnumerable<TSource>)	Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty.
	DefaultIfEmpty<TSource>(IEnumerable<TSource>, TSource)	Returns the elements of the specified sequence or the specified value in a singleton collection if the sequence is empty.
	Distinct<TSource>(IEnumerable<TSource>)	Returns distinct elements from a sequence by using the default equality comparer to compare values.
	Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)	Returns distinct elements from a sequence by using a specified IEqualityComparer<T> to compare values.
	ElementAt<TSource>(IEnumerable<TSource>, Int32)	Returns the element at a specified index in a sequence.
	ElementAtOrDefault<TSource>(IEnumerable<TSource>, Int32)	Returns the element at a specified index in a sequence or a default value if the index is out of range.
	Empty<TResult>()	Returns an empty IEnumerable<T> that has the specified type argument.
	Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)	Produces the set difference of two sequences by using the default equality comparer to compare values.
	Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)	Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values.
	First<TSource>(IEnumerable<TSource>)	Returns the first element of a sequence.
	First<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Returns the first element in a sequence that satisfies a specified condition.
	FirstOrDefault<TSource>(IEnumerable<TSource>)	Returns the first element of a sequence, or a default value if the sequence contains no elements.
	FirstOrDefault<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Returns the first element of the sequence that satisfies a condition or a default value if no such element is found.
	GroupBy<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>)	Groups the elements of a sequence according to a specified key selector function.
	GroupBy<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>, IEqualityComparer<TKey>)	Groups the elements of a sequence according to a specified key selector function and compares the keys by using a specified comparer.
	GroupBy<TSource, TKey, TElement>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>)	Groups the elements of a sequence according to a specified key selector function and projects the elements for each group by using a specified function.
	GroupBy<TSource, TKey, TElement>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>, IEqualityComparer<TKey>)	Groups the elements of a sequence according to a key selector function. The keys are compared by using a comparer and each group's elements are projected by using a specified function.
	GroupBy<TSource, TKey, TResult>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TKey, IEnumerable<TSource>, TResult>)	Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key.
	GroupBy<TSource, TKey, TResult>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TKey, IEnumerable<TSource>, TResult>, IEqualityComparer<TKey>)	Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The keys are compared by using a specified comparer.
	GroupBy<TSource, TKey, TElement, TResult>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>, Func<TKey, IEnumerable<TElement>, TResult>)	Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The elements of each group are projected by using a specified function.
	GroupBy<TSource, TKey, TElement, TResult>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>, Func<TKey, IEnumerable<TElement>, TResult>, IEqualityComparer<TKey>)	Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. Key values are compared by using a specified comparer, and the elements of each group are projected by using a specified function.
	GroupJoin<TOuter, TInner, TKey, TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, IEnumerable<TInner>, TResult>)	Correlates the elements of two sequences based on equality of keys and groups the results. The default equality comparer is used to compare keys.
	GroupJoin<TOuter, TInner, TKey, TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, IEnumerable<TInner>, TResult>, IEqualityComparer<TKey>)	Correlates the elements of two sequences based on key equality and groups the results. A specified IEqualityComparer<T> is used to compare keys.
	Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)	Produces the set intersection of two sequences by using the default equality comparer to compare values.
	Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)	Produces the set intersection of two sequences by using the specified IEqualityComparer<T> to compare values.
	Join<TOuter, TInner, TKey, TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, TInner, TResult>)	Correlates the elements of two sequences based on matching keys. The default equality comparer is used to compare keys.
	Join<TOuter, TInner, TKey, TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, TInner, TResult>, IEqualityComparer<TKey>)	Correlates the elements of two sequences based on matching keys. A specified IEqualityComparer<T> is used to compare keys.
	Last<TSource>(IEnumerable<TSource>)	Returns the last element of a sequence.
	Last<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Returns the last element of a sequence that satisfies a specified condition.
	LastOrDefault<TSource>(IEnumerable<TSource>)	Returns the last element of a sequence, or a default value if the sequence contains no elements.
	LastOrDefault<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Returns the last element of a sequence that satisfies a condition or a default value if no such element is found.
	LongCount<TSource>(IEnumerable<TSource>)	Returns an Int64 that represents the total number of elements in a sequence.
	LongCount<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Returns an Int64 that represents how many elements in a sequence satisfy a condition.
	Max(IEnumerable<Decimal>)	Returns the maximum value in a sequence of Decimal values.
	Max(IEnumerable<Double>)	Returns the maximum value in a sequence of Double values.
	Max(IEnumerable<Int32>)	Returns the maximum value in a sequence of Int32 values.
	Max(IEnumerable<Int64>)	Returns the maximum value in a sequence of Int64 values.
	Max(IEnumerable<Nullable<Decimal>>)	Returns the maximum value in a sequence of nullable Decimal values.
	Max(IEnumerable<Nullable<Double>>)	Returns the maximum value in a sequence of nullable Double values.
	Max(IEnumerable<Nullable<Int32>>)	Returns the maximum value in a sequence of nullable Int32 values.
	Max(IEnumerable<Nullable<Int64>>)	Returns the maximum value in a sequence of nullable Int64 values.
	Max(IEnumerable<Nullable<Single>>)	Returns the maximum value in a sequence of nullable Single values.
	Max(IEnumerable<Single>)	Returns the maximum value in a sequence of Single values.
	Max<TSource>(IEnumerable<TSource>)	Returns the maximum value in a generic sequence.
	Max<TSource>(IEnumerable<TSource>, Func<TSource, Decimal>)	Invokes a transform function on each element of a sequence and returns the maximum Decimal value.
	Max<TSource>(IEnumerable<TSource>, Func<TSource, Double>)	Invokes a transform function on each element of a sequence and returns the maximum Double value.
	Max<TSource>(IEnumerable<TSource>, Func<TSource, Int32>)	Invokes a transform function on each element of a sequence and returns the maximum Int32 value.
	Max<TSource>(IEnumerable<TSource>, Func<TSource, Int64>)	Invokes a transform function on each element of a sequence and returns the maximum Int64 value.
	Max<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Decimal>>)	Invokes a transform function on each element of a sequence and returns the maximum nullable Decimal value.
	Max<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Double>>)	Invokes a transform function on each element of a sequence and returns the maximum nullable Double value.
	Max<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Int32>>)	Invokes a transform function on each element of a sequence and returns the maximum nullable Int32 value.
	Max<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Int64>>)	Invokes a transform function on each element of a sequence and returns the maximum nullable Int64 value.
	Max<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Single>>)	Invokes a transform function on each element of a sequence and returns the maximum nullable Single value.
	Max<TSource>(IEnumerable<TSource>, Func<TSource, Single>)	Invokes a transform function on each element of a sequence and returns the maximum Single value.
	Max<TSource, TResult>(IEnumerable<TSource>, Func<TSource, TResult>)	Invokes a transform function on each element of a generic sequence and returns the maximum resulting value.
	Min(IEnumerable<Decimal>)	Returns the minimum value in a sequence of Decimal values.
	Min(IEnumerable<Double>)	Returns the minimum value in a sequence of Double values.
	Min(IEnumerable<Int32>)	Returns the minimum value in a sequence of Int32 values.
	Min(IEnumerable<Int64>)	Returns the minimum value in a sequence of Int64 values.
	Min(IEnumerable<Nullable<Decimal>>)	Returns the minimum value in a sequence of nullable Decimal values.
	Min(IEnumerable<Nullable<Double>>)	Returns the minimum value in a sequence of nullable Double values.
	Min(IEnumerable<Nullable<Int32>>)	Returns the minimum value in a sequence of nullable Int32 values.
	Min(IEnumerable<Nullable<Int64>>)	Returns the minimum value in a sequence of nullable Int64 values.
	Min(IEnumerable<Nullable<Single>>)	Returns the minimum value in a sequence of nullable Single values.
	Min(IEnumerable<Single>)	Returns the minimum value in a sequence of Single values.
	Min<TSource>(IEnumerable<TSource>)	Returns the minimum value in a generic sequence.
	Min<TSource>(IEnumerable<TSource>, Func<TSource, Decimal>)	Invokes a transform function on each element of a sequence and returns the minimum Decimal value.
	Min<TSource>(IEnumerable<TSource>, Func<TSource, Double>)	Invokes a transform function on each element of a sequence and returns the minimum Double value.
	Min<TSource>(IEnumerable<TSource>, Func<TSource, Int32>)	Invokes a transform function on each element of a sequence and returns the minimum Int32 value.
	Min<TSource>(IEnumerable<TSource>, Func<TSource, Int64>)	Invokes a transform function on each element of a sequence and returns the minimum Int64 value.
	Min<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Decimal>>)	Invokes a transform function on each element of a sequence and returns the minimum nullable Decimal value.
	Min<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Double>>)	Invokes a transform function on each element of a sequence and returns the minimum nullable Double value.
	Min<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Int32>>)	Invokes a transform function on each element of a sequence and returns the minimum nullable Int32 value.
	Min<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Int64>>)	Invokes a transform function on each element of a sequence and returns the minimum nullable Int64 value.
	Min<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Single>>)	Invokes a transform function on each element of a sequence and returns the minimum nullable Single value.
	Min<TSource>(IEnumerable<TSource>, Func<TSource, Single>)	Invokes a transform function on each element of a sequence and returns the minimum Single value.
	Min<TSource, TResult>(IEnumerable<TSource>, Func<TSource, TResult>)	Invokes a transform function on each element of a generic sequence and returns the minimum resulting value.
	OfType<TResult>(IEnumerable)	Filters the elements of an IEnumerable based on a specified type.
	OrderBy<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>)	Sorts the elements of a sequence in ascending order according to a key.
	OrderBy<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>, IComparer<TKey>)	Sorts the elements of a sequence in ascending order by using a specified comparer.
	OrderByDescending<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>)	Sorts the elements of a sequence in descending order according to a key.
	OrderByDescending<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>, IComparer<TKey>)	Sorts the elements of a sequence in descending order by using a specified comparer.
	Range(Int32, Int32)	Generates a sequence of integral numbers within a specified range.
	Repeat<TResult>(TResult, Int32)	Generates a sequence that contains one repeated value.
	Reverse<TSource>(IEnumerable<TSource>)	Inverts the order of the elements in a sequence.
	Select<TSource, TResult>(IEnumerable<TSource>, Func<TSource, TResult>)	Projects each element of a sequence into a new form.
	Select<TSource, TResult>(IEnumerable<TSource>, Func<TSource, Int32, TResult>)	Projects each element of a sequence into a new form by incorporating the element's index.
	SelectMany<TSource, TResult>(IEnumerable<TSource>, Func<TSource, IEnumerable<TResult>>)	Projects each element of a sequence to an IEnumerable<T> and flattens the resulting sequences into one sequence.
	SelectMany<TSource, TResult>(IEnumerable<TSource>, Func<TSource, Int32, IEnumerable<TResult>>)	Projects each element of a sequence to an IEnumerable<T>, and flattens the resulting sequences into one sequence. The index of each source element is used in the projected form of that element.
	SelectMany<TSource, TCollection, TResult>(IEnumerable<TSource>, Func<TSource, IEnumerable<TCollection>>, Func<TSource, TCollection, TResult>)	Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein.
	SelectMany<TSource, TCollection, TResult>(IEnumerable<TSource>, Func<TSource, Int32, IEnumerable<TCollection>>, Func<TSource, TCollection, TResult>)	Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. The index of each source element is used in the intermediate projected form of that element.
	SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)	Determines whether two sequences are equal by comparing the elements by using the default equality comparer for their type.
	SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)	Determines whether two sequences are equal by comparing their elements by using a specified IEqualityComparer<T>.
	Single<TSource>(IEnumerable<TSource>)	Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence.
	Single<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Returns the only element of a sequence that satisfies a specified condition, and throws an exception if more than one such element exists.
	SingleOrDefault<TSource>(IEnumerable<TSource>)	Returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.
	SingleOrDefault<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.
	Skip<TSource>(IEnumerable<TSource>, Int32)	Bypasses a specified number of elements in a sequence and then returns the remaining elements.
	SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.
	SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource, Int32, Boolean>)	Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. The element's index is used in the logic of the predicate function.
	Sum(IEnumerable<Decimal>)	Computes the sum of a sequence of Decimal values.
	Sum(IEnumerable<Double>)	Computes the sum of a sequence of Double values.
	Sum(IEnumerable<Int32>)	Computes the sum of a sequence of Int32 values.
	Sum(IEnumerable<Int64>)	Computes the sum of a sequence of Int64 values.
	Sum(IEnumerable<Nullable<Decimal>>)	Computes the sum of a sequence of nullable Decimal values.
	Sum(IEnumerable<Nullable<Double>>)	Computes the sum of a sequence of nullable Double values.
	Sum(IEnumerable<Nullable<Int32>>)	Computes the sum of a sequence of nullable Int32 values.
	Sum(IEnumerable<Nullable<Int64>>)	Computes the sum of a sequence of nullable Int64 values.
	Sum(IEnumerable<Nullable<Single>>)	Computes the sum of a sequence of nullable Single values.
	Sum(IEnumerable<Single>)	Computes the sum of a sequence of Single values.
	Sum<TSource>(IEnumerable<TSource>, Func<TSource, Decimal>)	Computes the sum of the sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence.
	Sum<TSource>(IEnumerable<TSource>, Func<TSource, Double>)	Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.
	Sum<TSource>(IEnumerable<TSource>, Func<TSource, Int32>)	Computes the sum of the sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence.
	Sum<TSource>(IEnumerable<TSource>, Func<TSource, Int64>)	Computes the sum of the sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence.
	Sum<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Decimal>>)	Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence.
	Sum<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Double>>)	Computes the sum of the sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence.
	Sum<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Int32>>)	Computes the sum of the sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.
	Sum<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Int64>>)	Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.
	Sum<TSource>(IEnumerable<TSource>, Func<TSource, Nullable<Single>>)	Computes the sum of the sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence.
	Sum<TSource>(IEnumerable<TSource>, Func<TSource, Single>)	Computes the sum of the sequence of Single values that are obtained by invoking a transform function on each element of the input sequence.
	Take<TSource>(IEnumerable<TSource>, Int32)	Returns a specified number of contiguous elements from the start of a sequence.
	TakeWhile<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Returns elements from a sequence as long as a specified condition is true.
	TakeWhile<TSource>(IEnumerable<TSource>, Func<TSource, Int32, Boolean>)	Returns elements from a sequence as long as a specified condition is true. The element's index is used in the logic of the predicate function.
	ThenBy<TSource, TKey>(IOrderedEnumerable<TSource>, Func<TSource, TKey>)	Performs a subsequent ordering of the elements in a sequence in ascending order according to a key.
	ThenBy<TSource, TKey>(IOrderedEnumerable<TSource>, Func<TSource, TKey>, IComparer<TKey>)	Performs a subsequent ordering of the elements in a sequence in ascending order by using a specified comparer.
	ThenByDescending<TSource, TKey>(IOrderedEnumerable<TSource>, Func<TSource, TKey>)	Performs a subsequent ordering of the elements in a sequence in descending order, according to a key.
	ThenByDescending<TSource, TKey>(IOrderedEnumerable<TSource>, Func<TSource, TKey>, IComparer<TKey>)	Performs a subsequent ordering of the elements in a sequence in descending order by using a specified comparer.
	ToArray<TSource>(IEnumerable<TSource>)	Creates an array from a IEnumerable<T>.
	ToDictionary<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>)	Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function.
	ToDictionary<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>, IEqualityComparer<TKey>)	Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function and key comparer.
	ToDictionary<TSource, TKey, TElement>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>)	Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to specified key selector and element selector functions.
	ToDictionary<TSource, TKey, TElement>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>, IEqualityComparer<TKey>)	Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function, a comparer, and an element selector function.
	ToList<TSource>(IEnumerable<TSource>)	Creates a List<T> from an IEnumerable<T>.
	ToLookup<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>)	Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function.
	ToLookup<TSource, TKey>(IEnumerable<TSource>, Func<TSource, TKey>, IEqualityComparer<TKey>)	Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function and key comparer.
	ToLookup<TSource, TKey, TElement>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>)	Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to specified key selector and element selector functions.
	ToLookup<TSource, TKey, TElement>(IEnumerable<TSource>, Func<TSource, TKey>, Func<TSource, TElement>, IEqualityComparer<TKey>)	Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function, a comparer and an element selector function.
	Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)	Produces the set union of two sequences by using the default equality comparer.
	Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)	Produces the set union of two sequences by using a specified IEqualityComparer<T>.
	Where<TSource>(IEnumerable<TSource>, Func<TSource, Boolean>)	Filters a sequence of values based on a predicate.
	Where<TSource>(IEnumerable<TSource>, Func<TSource, Int32, Boolean>)	Filters a sequence of values based on a predicate. Each element's index is used in the logic of the predicate function.
	Zip<TFirst, TSecond, TResult>(IEnumerable<TFirst>, IEnumerable<TSecond>, Func<TFirst, TSecond, TResult>)	Applies a specified function to the corresponding elements of two sequences, producing a sequence of the results.

IEnumerable<T> Interface

https://msdn.microsoft.com/en-us/library/9eekhta0(v=vs.110).aspx

Exposes the enumerator, which supports a simple iteration over a collection of a specified type.

To browse the .NET Framework source code for this type, see the Reference Source.

Namespace:   System.Collections.Generic
Assembly:  mscorlib (in mscorlib.dll)

Syntax

C#

C++

F#

VB

public interface IEnumerable<out T> : IEnumerable

Type Parameters

out T

The type of objects to enumerate.

Methods

	Name	Description
	GetEnumerator()	Returns an enumerator that iterates through the collection.

Extension Methods

	Name	Description
	Aggregate<TSource>(Func<TSource, TSource, TSource>)	Overloaded. Applies an accumulator function over a sequence.(Defined by Enumerable.)
	Aggregate<TSource, TAccumulate>(TAccumulate, Func<TAccumulate, TSource, TAccumulate>)	Overloaded. Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value.(Defined by Enumerable.)
	Aggregate<TSource, TAccumulate, TResult>(TAccumulate, Func<TAccumulate, TSource, TAccumulate>, Func<TAccumulate, TResult>)	Overloaded. Applies an accumulator function over a sequence. The specified seed value is used as the initial accumulator value, and the specified function is used to select the result value.(Defined by Enumerable.)
	All<TSource>(Func<TSource, Boolean>)	Determines whether all elements of a sequence satisfy a condition.(Defined by Enumerable.)
	Ancestors<T>()	Overloaded. Returns a collection of elements that contains the ancestors of every node in the source collection.(Defined by Extensions.)
	Ancestors<T>(XName)	Overloaded. Returns a filtered collection of elements that contains the ancestors of every node in the source collection. Only elements that have a matching XName are included in the collection.(Defined by Extensions.)
	Any<TSource>()	Overloaded. Determines whether a sequence contains any elements.(Defined by Enumerable.)
	Any<TSource>(Func<TSource, Boolean>)	Overloaded. Determines whether any element of a sequence satisfies a condition.(Defined by Enumerable.)
	AsEnumerable<TSource>()	Returns the input typed as IEnumerable<T>.(Defined by Enumerable.)
	AsParallel<TSource>()	Overloaded. Enables parallelization of a query.(Defined by ParallelEnumerable.)
	AsQueryable<TElement>()	Overloaded. Converts a generic IEnumerable<T> to a generic IQueryable<T>.(Defined by Queryable.)
	Average<TSource>(Func<TSource, Decimal>)	Overloaded. Computes the average of a sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Average<TSource>(Func<TSource, Double>)	Overloaded. Computes the average of a sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Average<TSource>(Func<TSource, Int32>)	Overloaded. Computes the average of a sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Average<TSource>(Func<TSource, Int64>)	Overloaded. Computes the average of a sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Average<TSource>(Func<TSource, Nullable<Decimal>>)	Overloaded. Computes the average of a sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Average<TSource>(Func<TSource, Nullable<Double>>)	Overloaded. Computes the average of a sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Average<TSource>(Func<TSource, Nullable<Int32>>)	Overloaded. Computes the average of a sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Average<TSource>(Func<TSource, Nullable<Int64>>)	Overloaded. Computes the average of a sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Average<TSource>(Func<TSource, Nullable<Single>>)	Overloaded. Computes the average of a sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Average<TSource>(Func<TSource, Single>)	Overloaded. Computes the average of a sequence of Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Cast<TResult>()	Casts the elements of an IEnumerable to the specified type.(Defined by Enumerable.)
	Concat<TSource>(IEnumerable<TSource>)	Concatenates two sequences.(Defined by Enumerable.)
	Contains<TSource>(TSource)	Overloaded. Determines whether a sequence contains a specified element by using the default equality comparer.(Defined by Enumerable.)
	Contains<TSource>(TSource, IEqualityComparer<TSource>)	Overloaded. Determines whether a sequence contains a specified element by using a specified IEqualityComparer<T>.(Defined by Enumerable.)
	CopyToDataTable<T>()	Overloaded. Returns a DataTable that contains copies of the DataRow objects, given an input IEnumerable<T> object where the generic parameter T is DataRow. (Defined by DataTableExtensions.)
	CopyToDataTable<T>(DataTable, LoadOption)	Overloaded. Copies DataRow objects to the specified DataTable, given an input IEnumerable<T> object where the generic parameter T is DataRow.(Defined by DataTableExtensions.)
	CopyToDataTable<T>(DataTable, LoadOption, FillErrorEventHandler)	Overloaded. Copies DataRow objects to the specified DataTable, given an input IEnumerable<T> object where the generic parameter T is DataRow.(Defined by DataTableExtensions.)
	Count<TSource>()	Overloaded. Returns the number of elements in a sequence.(Defined by Enumerable.)
	Count<TSource>(Func<TSource, Boolean>)	Overloaded. Returns a number that represents how many elements in the specified sequence satisfy a condition.(Defined by Enumerable.)
	DefaultIfEmpty<TSource>()	Overloaded. Returns the elements of the specified sequence or the type parameter's default value in a singleton collection if the sequence is empty.(Defined by Enumerable.)
	DefaultIfEmpty<TSource>(TSource)	Overloaded. Returns the elements of the specified sequence or the specified value in a singleton collection if the sequence is empty.(Defined by Enumerable.)
	DescendantNodes<T>()	Returns a collection of the descendant nodes of every document and element in the source collection.(Defined by Extensions.)
	Descendants<T>()	Overloaded. Returns a collection of elements that contains the descendant elements of every element and document in the source collection.(Defined by Extensions.)
	Descendants<T>(XName)	Overloaded. Returns a filtered collection of elements that contains the descendant elements of every element and document in the source collection. Only elements that have a matching XName are included in the collection.(Defined by Extensions.)
	Distinct<TSource>()	Overloaded. Returns distinct elements from a sequence by using the default equality comparer to compare values.(Defined by Enumerable.)
	Distinct<TSource>(IEqualityComparer<TSource>)	Overloaded. Returns distinct elements from a sequence by using a specified IEqualityComparer<T> to compare values.(Defined by Enumerable.)
	ElementAt<TSource>(Int32)	Returns the element at a specified index in a sequence.(Defined by Enumerable.)
	ElementAtOrDefault<TSource>(Int32)	Returns the element at a specified index in a sequence or a default value if the index is out of range.(Defined by Enumerable.)
	Elements<T>()	Overloaded. Returns a collection of the child elements of every element and document in the source collection.(Defined by Extensions.)
	Elements<T>(XName)	Overloaded. Returns a filtered collection of the child elements of every element and document in the source collection. Only elements that have a matching XName are included in the collection.(Defined by Extensions.)
	Except<TSource>(IEnumerable<TSource>)	Overloaded. Produces the set difference of two sequences by using the default equality comparer to compare values.(Defined by Enumerable.)
	Except<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)	Overloaded. Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values.(Defined by Enumerable.)
	First<TSource>()	Overloaded. Returns the first element of a sequence.(Defined by Enumerable.)
	First<TSource>(Func<TSource, Boolean>)	Overloaded. Returns the first element in a sequence that satisfies a specified condition.(Defined by Enumerable.)
	FirstOrDefault<TSource>()	Overloaded. Returns the first element of a sequence, or a default value if the sequence contains no elements.(Defined by Enumerable.)
	FirstOrDefault<TSource>(Func<TSource, Boolean>)	Overloaded. Returns the first element of the sequence that satisfies a condition or a default value if no such element is found.(Defined by Enumerable.)
	GroupBy<TSource, TKey>(Func<TSource, TKey>)	Overloaded. Groups the elements of a sequence according to a specified key selector function.(Defined by Enumerable.)
	GroupBy<TSource, TKey>(Func<TSource, TKey>, IEqualityComparer<TKey>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and compares the keys by using a specified comparer.(Defined by Enumerable.)
	GroupBy<TSource, TKey, TElement>(Func<TSource, TKey>, Func<TSource, TElement>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and projects the elements for each group by using a specified function.(Defined by Enumerable.)
	GroupBy<TSource, TKey, TElement>(Func<TSource, TKey>, Func<TSource, TElement>, IEqualityComparer<TKey>)	Overloaded. Groups the elements of a sequence according to a key selector function. The keys are compared by using a comparer and each group's elements are projected by using a specified function.(Defined by Enumerable.)
	GroupBy<TSource, TKey, TResult>(Func<TSource, TKey>, Func<TKey, IEnumerable<TSource>, TResult>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key.(Defined by Enumerable.)
	GroupBy<TSource, TKey, TResult>(Func<TSource, TKey>, Func<TKey, IEnumerable<TSource>, TResult>, IEqualityComparer<TKey>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The keys are compared by using a specified comparer.(Defined by Enumerable.)
	GroupBy<TSource, TKey, TElement, TResult>(Func<TSource, TKey>, Func<TSource, TElement>, Func<TKey, IEnumerable<TElement>, TResult>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. The elements of each group are projected by using a specified function.(Defined by Enumerable.)
	GroupBy<TSource, TKey, TElement, TResult>(Func<TSource, TKey>, Func<TSource, TElement>, Func<TKey, IEnumerable<TElement>, TResult>, IEqualityComparer<TKey>)	Overloaded. Groups the elements of a sequence according to a specified key selector function and creates a result value from each group and its key. Key values are compared by using a specified comparer, and the elements of each group are projected by using a specified function.(Defined by Enumerable.)
	GroupJoin<TOuter, TInner, TKey, TResult>(IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, IEnumerable<TInner>, TResult>)	Overloaded. Correlates the elements of two sequences based on equality of keys and groups the results. The default equality comparer is used to compare keys.(Defined by Enumerable.)
	GroupJoin<TOuter, TInner, TKey, TResult>(IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, IEnumerable<TInner>, TResult>, IEqualityComparer<TKey>)	Overloaded. Correlates the elements of two sequences based on key equality and groups the results. A specified IEqualityComparer<T> is used to compare keys.(Defined by Enumerable.)
	InDocumentOrder<T>()	Returns a collection of nodes that contains all nodes in the source collection, sorted in document order.(Defined by Extensions.)
	Intersect<TSource>(IEnumerable<TSource>)	Overloaded. Produces the set intersection of two sequences by using the default equality comparer to compare values.(Defined by Enumerable.)
	Intersect<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)	Overloaded. Produces the set intersection of two sequences by using the specified IEqualityComparer<T> to compare values.(Defined by Enumerable.)
	Join<TOuter, TInner, TKey, TResult>(IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, TInner, TResult>)	Overloaded. Correlates the elements of two sequences based on matching keys. The default equality comparer is used to compare keys.(Defined by Enumerable.)
	Join<TOuter, TInner, TKey, TResult>(IEnumerable<TInner>, Func<TOuter, TKey>, Func<TInner, TKey>, Func<TOuter, TInner, TResult>, IEqualityComparer<TKey>)	Overloaded. Correlates the elements of two sequences based on matching keys. A specified IEqualityComparer<T> is used to compare keys.(Defined by Enumerable.)
	Last<TSource>()	Overloaded. Returns the last element of a sequence.(Defined by Enumerable.)
	Last<TSource>(Func<TSource, Boolean>)	Overloaded. Returns the last element of a sequence that satisfies a specified condition.(Defined by Enumerable.)
	LastOrDefault<TSource>()	Overloaded. Returns the last element of a sequence, or a default value if the sequence contains no elements.(Defined by Enumerable.)
	LastOrDefault<TSource>(Func<TSource, Boolean>)	Overloaded. Returns the last element of a sequence that satisfies a condition or a default value if no such element is found.(Defined by Enumerable.)
	LongCount<TSource>()	Overloaded. Returns an Int64 that represents the total number of elements in a sequence.(Defined by Enumerable.)
	LongCount<TSource>(Func<TSource, Boolean>)	Overloaded. Returns an Int64 that represents how many elements in a sequence satisfy a condition.(Defined by Enumerable.)
	Max<TSource>()	Overloaded. Returns the maximum value in a generic sequence.(Defined by Enumerable.)
	Max<TSource>(Func<TSource, Decimal>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Decimal value.(Defined by Enumerable.)
	Max<TSource>(Func<TSource, Double>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Double value.(Defined by Enumerable.)
	Max<TSource>(Func<TSource, Int32>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Int32 value.(Defined by Enumerable.)
	Max<TSource>(Func<TSource, Int64>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Int64 value.(Defined by Enumerable.)
	Max<TSource>(Func<TSource, Nullable<Decimal>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Decimal value.(Defined by Enumerable.)
	Max<TSource>(Func<TSource, Nullable<Double>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Double value.(Defined by Enumerable.)
	Max<TSource>(Func<TSource, Nullable<Int32>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Int32 value.(Defined by Enumerable.)
	Max<TSource>(Func<TSource, Nullable<Int64>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Int64 value.(Defined by Enumerable.)
	Max<TSource>(Func<TSource, Nullable<Single>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum nullable Single value.(Defined by Enumerable.)
	Max<TSource>(Func<TSource, Single>)	Overloaded. Invokes a transform function on each element of a sequence and returns the maximum Single value.(Defined by Enumerable.)
	Max<TSource, TResult>(Func<TSource, TResult>)	Overloaded. Invokes a transform function on each element of a generic sequence and returns the maximum resulting value.(Defined by Enumerable.)
	Min<TSource>()	Overloaded. Returns the minimum value in a generic sequence.(Defined by Enumerable.)
	Min<TSource>(Func<TSource, Decimal>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Decimal value.(Defined by Enumerable.)
	Min<TSource>(Func<TSource, Double>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Double value.(Defined by Enumerable.)
	Min<TSource>(Func<TSource, Int32>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Int32 value.(Defined by Enumerable.)
	Min<TSource>(Func<TSource, Int64>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Int64 value.(Defined by Enumerable.)
	Min<TSource>(Func<TSource, Nullable<Decimal>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Decimal value.(Defined by Enumerable.)
	Min<TSource>(Func<TSource, Nullable<Double>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Double value.(Defined by Enumerable.)
	Min<TSource>(Func<TSource, Nullable<Int32>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Int32 value.(Defined by Enumerable.)
	Min<TSource>(Func<TSource, Nullable<Int64>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Int64 value.(Defined by Enumerable.)
	Min<TSource>(Func<TSource, Nullable<Single>>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum nullable Single value.(Defined by Enumerable.)
	Min<TSource>(Func<TSource, Single>)	Overloaded. Invokes a transform function on each element of a sequence and returns the minimum Single value.(Defined by Enumerable.)
	Min<TSource, TResult>(Func<TSource, TResult>)	Overloaded. Invokes a transform function on each element of a generic sequence and returns the minimum resulting value.(Defined by Enumerable.)
	Nodes<T>()	Returns a collection of the child nodes of every document and element in the source collection.(Defined by Extensions.)
	OfType<TResult>()	Filters the elements of an IEnumerable based on a specified type.(Defined by Enumerable.)
	OrderBy<TSource, TKey>(Func<TSource, TKey>)	Overloaded. Sorts the elements of a sequence in ascending order according to a key.(Defined by Enumerable.)
	OrderBy<TSource, TKey>(Func<TSource, TKey>, IComparer<TKey>)	Overloaded. Sorts the elements of a sequence in ascending order by using a specified comparer.(Defined by Enumerable.)
	OrderByDescending<TSource, TKey>(Func<TSource, TKey>)	Overloaded. Sorts the elements of a sequence in descending order according to a key.(Defined by Enumerable.)
	OrderByDescending<TSource, TKey>(Func<TSource, TKey>, IComparer<TKey>)	Overloaded. Sorts the elements of a sequence in descending order by using a specified comparer.(Defined by Enumerable.)
	Remove<T>()	Overloaded. Removes every node in the source collection from its parent node.(Defined by Extensions.)
	Reverse<TSource>()	Inverts the order of the elements in a sequence.(Defined by Enumerable.)
	Select<TSource, TResult>(Func<TSource, TResult>)	Overloaded. Projects each element of a sequence into a new form.(Defined by Enumerable.)
	Select<TSource, TResult>(Func<TSource, Int32, TResult>)	Overloaded. Projects each element of a sequence into a new form by incorporating the element's index.(Defined by Enumerable.)
	SelectMany<TSource, TResult>(Func<TSource, IEnumerable<TResult>>)	Overloaded. Projects each element of a sequence to an IEnumerable<T> and flattens the resulting sequences into one sequence.(Defined by Enumerable.)
	SelectMany<TSource, TResult>(Func<TSource, Int32, IEnumerable<TResult>>)	Overloaded. Projects each element of a sequence to an IEnumerable<T>, and flattens the resulting sequences into one sequence. The index of each source element is used in the projected form of that element.(Defined by Enumerable.)
	SelectMany<TSource, TCollection, TResult>(Func<TSource, IEnumerable<TCollection>>, Func<TSource, TCollection, TResult>)	Overloaded. Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein.(Defined by Enumerable.)
	SelectMany<TSource, TCollection, TResult>(Func<TSource, Int32, IEnumerable<TCollection>>, Func<TSource, TCollection, TResult>)	Overloaded. Projects each element of a sequence to an IEnumerable<T>, flattens the resulting sequences into one sequence, and invokes a result selector function on each element therein. The index of each source element is used in the intermediate projected form of that element.(Defined by Enumerable.)
	SequenceEqual<TSource>(IEnumerable<TSource>)	Overloaded. Determines whether two sequences are equal by comparing the elements by using the default equality comparer for their type.(Defined by Enumerable.)
	SequenceEqual<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)	Overloaded. Determines whether two sequences are equal by comparing their elements by using a specified IEqualityComparer<T>.(Defined by Enumerable.)
	Single<TSource>()	Overloaded. Returns the only element of a sequence, and throws an exception if there is not exactly one element in the sequence.(Defined by Enumerable.)
	Single<TSource>(Func<TSource, Boolean>)	Overloaded. Returns the only element of a sequence that satisfies a specified condition, and throws an exception if more than one such element exists.(Defined by Enumerable.)
	SingleOrDefault<TSource>()	Overloaded. Returns the only element of a sequence, or a default value if the sequence is empty; this method throws an exception if there is more than one element in the sequence.(Defined by Enumerable.)
	SingleOrDefault<TSource>(Func<TSource, Boolean>)	Overloaded. Returns the only element of a sequence that satisfies a specified condition or a default value if no such element exists; this method throws an exception if more than one element satisfies the condition.(Defined by Enumerable.)
	Skip<TSource>(Int32)	Bypasses a specified number of elements in a sequence and then returns the remaining elements.(Defined by Enumerable.)
	SkipWhile<TSource>(Func<TSource, Boolean>)	Overloaded. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements.(Defined by Enumerable.)
	SkipWhile<TSource>(Func<TSource, Int32, Boolean>)	Overloaded. Bypasses elements in a sequence as long as a specified condition is true and then returns the remaining elements. The element's index is used in the logic of the predicate function.(Defined by Enumerable.)
	Sum<TSource>(Func<TSource, Decimal>)	Overloaded. Computes the sum of the sequence of Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Sum<TSource>(Func<TSource, Double>)	Overloaded. Computes the sum of the sequence of Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Sum<TSource>(Func<TSource, Int32>)	Overloaded. Computes the sum of the sequence of Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Sum<TSource>(Func<TSource, Int64>)	Overloaded. Computes the sum of the sequence of Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Sum<TSource>(Func<TSource, Nullable<Decimal>>)	Overloaded. Computes the sum of the sequence of nullable Decimal values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Sum<TSource>(Func<TSource, Nullable<Double>>)	Overloaded. Computes the sum of the sequence of nullable Double values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Sum<TSource>(Func<TSource, Nullable<Int32>>)	Overloaded. Computes the sum of the sequence of nullable Int32 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Sum<TSource>(Func<TSource, Nullable<Int64>>)	Overloaded. Computes the sum of the sequence of nullable Int64 values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Sum<TSource>(Func<TSource, Nullable<Single>>)	Overloaded. Computes the sum of the sequence of nullable Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Sum<TSource>(Func<TSource, Single>)	Overloaded. Computes the sum of the sequence of Single values that are obtained by invoking a transform function on each element of the input sequence.(Defined by Enumerable.)
	Take<TSource>(Int32)	Returns a specified number of contiguous elements from the start of a sequence.(Defined by Enumerable.)
	TakeWhile<TSource>(Func<TSource, Boolean>)	Overloaded. Returns elements from a sequence as long as a specified condition is true.(Defined by Enumerable.)
	TakeWhile<TSource>(Func<TSource, Int32, Boolean>)	Overloaded. Returns elements from a sequence as long as a specified condition is true. The element's index is used in the logic of the predicate function.(Defined by Enumerable.)
	ToArray<TSource>()	Creates an array from a IEnumerable<T>.(Defined by Enumerable.)
	ToDictionary<TSource, TKey>(Func<TSource, TKey>)	Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function.(Defined by Enumerable.)
	ToDictionary<TSource, TKey>(Func<TSource, TKey>, IEqualityComparer<TKey>)	Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function and key comparer.(Defined by Enumerable.)
	ToDictionary<TSource, TKey, TElement>(Func<TSource, TKey>, Func<TSource, TElement>)	Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to specified key selector and element selector functions.(Defined by Enumerable.)
	ToDictionary<TSource, TKey, TElement>(Func<TSource, TKey>, Func<TSource, TElement>, IEqualityComparer<TKey>)	Overloaded. Creates a Dictionary<TKey, TValue> from an IEnumerable<T> according to a specified key selector function, a comparer, and an element selector function.(Defined by Enumerable.)
	ToList<TSource>()	Creates a List<T> from an IEnumerable<T>.(Defined by Enumerable.)
	ToLookup<TSource, TKey>(Func<TSource, TKey>)	Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function.(Defined by Enumerable.)
	ToLookup<TSource, TKey>(Func<TSource, TKey>, IEqualityComparer<TKey>)	Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function and key comparer.(Defined by Enumerable.)
	ToLookup<TSource, TKey, TElement>(Func<TSource, TKey>, Func<TSource, TElement>)	Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to specified key selector and element selector functions.(Defined by Enumerable.)
	ToLookup<TSource, TKey, TElement>(Func<TSource, TKey>, Func<TSource, TElement>, IEqualityComparer<TKey>)	Overloaded. Creates a Lookup<TKey, TElement> from an IEnumerable<T> according to a specified key selector function, a comparer and an element selector function.(Defined by Enumerable.)
	Union<TSource>(IEnumerable<TSource>)	Overloaded. Produces the set union of two sequences by using the default equality comparer.(Defined by Enumerable.)
	Union<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)	Overloaded. Produces the set union of two sequences by using a specified IEqualityComparer<T>.(Defined by Enumerable.)
	Where<TSource>(Func<TSource, Boolean>)	Overloaded. Filters a sequence of values based on a predicate.(Defined by Enumerable.)
	Where<TSource>(Func<TSource, Int32, Boolean>)	Overloaded. Filters a sequence of values based on a predicate. Each element's index is used in the logic of the predicate function.(Defined by Enumerable.)
	Zip<TFirst, TSecond, TResult>(IEnumerable<TSecond>, Func<TFirst, TSecond, TResult>)	Applies a specified function to the corresponding elements of two sequences, producing a sequence of the results.(Defined by Enumerable.)

Remarks

Note
To view the .NET Framework source code for this type, see the Reference Source. You can browse through the source code online, download the reference for offline viewing, and step through the sources (including patches and updates) during debugging; see instructions.

IEnumerable<T> is the base interface for collections in the System.Collections.Generic namespace such as List<T>, Dictionary<TKey, TValue>, and Stack<T> and other generic collections such as ObservableCollection<T> and ConcurrentStack<T>. Collections that implement IEnumerable<T> can be enumerated by using the foreach statement. For the non-generic version of this interface, see System.Collections.IEnumerable.

For the non-generic version of this interface, see System.Collections.IEnumerable.

IEnumerable<T> contains a single method that you must implement when implementing this interface; GetEnumerator, which returns an IEnumerator<T> object. The returned IEnumerator<T> provides the ability to iterate through the collection by exposing a Current property.

Notes to Implementers:

IEnumerable<T> is included for parity with non-generic collections; implementing IEnumerable<T> allows a generic collection to be passed to a method that expects an IEnumerable object.

Examples

The following example demonstrates how to implement the IEnumerable<T> interface and how to use that implementation to create a LINQ query. When you implement IEnumerable<T>, you must also implement IEnumerator<T> or, for C# only, you can use the yield (C# Reference) keyword. Implementing IEnumerator<T> also requires IDisposable to be implemented, which you will see in this example.

C#

VB

using System;
using System.IO;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

public class App
{
    // Excercise the Iterator and show that it's more
    // performant.
    public static void Main()
    {
        TestStreamReaderEnumerable();
        Console.WriteLine("---");
        TestReadingFile();
    }

    public static void TestStreamReaderEnumerable()
	{
		// Check the memory before the iterator is used.
		long memoryBefore = GC.GetTotalMemory(true);
      IEnumerable<String> stringsFound;
		// Open a file with the StreamReaderEnumerable and check for a string.
      try {
         stringsFound =
               from line in new StreamReaderEnumerable(@"c:\temp\tempFile.txt")
               where line.Contains("string to search for")
               select line;
         Console.WriteLine("Found: " + stringsFound.Count());
      }
      catch (FileNotFoundException) {
         Console.WriteLine(@"This example requires a file named C:\temp\tempFile.txt.");
         return;
      }

		// Check the memory after the iterator and output it to the console.
		long memoryAfter = GC.GetTotalMemory(false);
		Console.WriteLine("Memory Used With Iterator = \t"
            + string.Format(((memoryAfter - memoryBefore) / 1000).ToString(), "n") + "kb");
	}

    public static void TestReadingFile()
	{
		long memoryBefore = GC.GetTotalMemory(true);
      StreamReader sr;
      try {
         sr = File.OpenText("c:\\temp\\tempFile.txt");
      }
      catch (FileNotFoundException) {
         Console.WriteLine(@"This example requires a file named C:\temp\tempFile.txt.");
         return;
      }

        // Add the file contents to a generic list of strings.
		List<string> fileContents = new List<string>();
		while (!sr.EndOfStream) {
			fileContents.Add(sr.ReadLine());
		}

		// Check for the string.
		var stringsFound = 
            from line in fileContents
            where line.Contains("string to search for")
            select line;

        sr.Close();
        Console.WriteLine("Found: " + stringsFound.Count());

		// Check the memory after when the iterator is not used, and output it to the console.
		long memoryAfter = GC.GetTotalMemory(false);
		Console.WriteLine("Memory Used Without Iterator = \t" + 
            string.Format(((memoryAfter - memoryBefore) / 1000).ToString(), "n") + "kb");
	}
}

// A custom class that implements IEnumerable(T). When you implement IEnumerable(T), 
// you must also implement IEnumerable and IEnumerator(T).
public class StreamReaderEnumerable : IEnumerable<string>
{
    private string _filePath;
    public StreamReaderEnumerable(string filePath)
    {
        _filePath = filePath;
    }

    // Must implement GetEnumerator, which returns a new StreamReaderEnumerator.
    public IEnumerator<string> GetEnumerator()
    {
        return new StreamReaderEnumerator(_filePath);
    }

    // Must also implement IEnumerable.GetEnumerator, but implement as a private method.
    private IEnumerator GetEnumerator1()
    {
        return this.GetEnumerator();
    }
    IEnumerator IEnumerable.GetEnumerator()
    {
        return GetEnumerator1();
    }
}

// When you implement IEnumerable(T), you must also implement IEnumerator(T), 
// which will walk through the contents of the file one line at a time.
// Implementing IEnumerator(T) requires that you implement IEnumerator and IDisposable.
public class StreamReaderEnumerator : IEnumerator<string>
{
    private StreamReader _sr;
    public StreamReaderEnumerator(string filePath)
    {
        _sr = new StreamReader(filePath);
    }

    private string _current;
    // Implement the IEnumerator(T).Current publicly, but implement 
    // IEnumerator.Current, which is also required, privately.
    public string Current
    {

        get
        {
            if (_sr == null || _current == null)
            {
                throw new InvalidOperationException();
            }

            return _current;
        }
    }

    private object Current1
    {

        get { return this.Current; }
    }

    object IEnumerator.Current
    {
        get { return Current1; }
    }

    // Implement MoveNext and Reset, which are required by IEnumerator.
    public bool MoveNext()
    {
        _current = _sr.ReadLine();
        if (_current == null)
            return false;
        return true;
    }

    public void Reset()
    {
        _sr.DiscardBufferedData();
        _sr.BaseStream.Seek(0, SeekOrigin.Begin);
        _current = null;
    }

    // Implement IDisposable, which is also implemented by IEnumerator(T).
    private bool disposedValue = false;
    public void Dispose()
    {
        Dispose(true);
        GC.SuppressFinalize(this);
    }

    protected virtual void Dispose(bool disposing)
    {
        if (!this.disposedValue)
        {
            if (disposing)
            {
                // Dispose of managed resources.
            }
            _current = null;
            if (_sr != null) {
               _sr.Close();
               _sr.Dispose();
            }
        }

        this.disposedValue = true;
    }

     ~StreamReaderEnumerator()
    {
        Dispose(false);
    }
}
// This example displays output similar to the following:
//       Found: 2
//       Memory Used With Iterator =     33kb
//       ---
//       Found: 2
//       Memory Used Without Iterator =  206kb

For another C# example that demonstrates how to implement the IEnumerable<T> interface, see the Generics Sample. This sample uses the yield keyword instead of implementing IEnumerator<T>.