Enumerable Class

Definition

Namespace:

System.Linq

Assembly:

System.Linq.dll

Source:

Enumerable.cs

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

public ref class Enumerable abstract sealed

public static class Enumerable

type Enumerable = class

Public Module Enumerable

Inheritance

Object

Enumerable

Remarks

The methods in this class provide an implementation of the standard query operators for querying data sources that implement IEnumerable<T>. The standard query operators are general purpose methods that follow the LINQ pattern and enable you to express traversal, filter, and projection operations over data in any .NET-based programming language.

The majority of the methods in this class are defined as extension methods that extend IEnumerable<T>. This means they can be called like an instance method on any object that implements IEnumerable<T>.

Methods that are used in a query that returns a sequence of values do not consume the target data until the query object is enumerated. This is known as deferred execution. Methods that are used in a query that returns a singleton value execute and consume the target data immediately.

Methods

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.
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>(IEnumerable<TSource>, Func<TSource,TSource,TSource>)	Applies an accumulator function over a sequence.
All<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)	Determines whether all elements of a sequence satisfy a condition.
Any<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)	Determines whether any element of a sequence satisfies a condition.
Any<TSource>(IEnumerable<TSource>)	Determines whether a sequence contains any elements.
Append<TSource>(IEnumerable<TSource>, TSource)	Appends a value to the end of the sequence.
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.
Chunk<TSource>(IEnumerable<TSource>, Int32)	Splits the elements of a sequence into chunks of size at most size.
Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)	Concatenates two sequences.
Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>)	Determines whether a sequence contains a specified element by using a specified IEqualityComparer<T>.
Contains<TSource>(IEnumerable<TSource>, TSource)	Determines whether a sequence contains a specified element by using the default equality comparer.
Count<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)	Returns a number that represents how many elements in the specified sequence satisfy a condition.
Count<TSource>(IEnumerable<TSource>)	Returns the number of elements in a sequence.
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.
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.
Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)	Returns distinct elements from a sequence by using a specified IEqualityComparer<T> to compare values.
Distinct<TSource>(IEnumerable<TSource>)	Returns distinct elements from a sequence by using the default equality comparer to compare values.
DistinctBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>)	Returns distinct elements from a sequence according to a specified key selector function and using a specified comparer to compare keys.
DistinctBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)	Returns distinct elements from a sequence according to a specified key selector function.
ElementAt<TSource>(IEnumerable<TSource>, Index)	Returns the element at a specified index in a sequence.
ElementAt<TSource>(IEnumerable<TSource>, Int32)	Returns the element at a specified index in a sequence.
ElementAtOrDefault<TSource>(IEnumerable<TSource>, Index)	Returns the element at a specified index in a sequence or a default value if the index is out of range.
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>, IEqualityComparer<TSource>)	Produces the set difference of two sequences by using the specified IEqualityComparer<T> to compare values.
Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)	Produces the set difference of two sequences by using the default equality comparer to compare values.
ExceptBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TKey>, Func<TSource,TKey>, IEqualityComparer<TKey>)	Produces the set difference of two sequences according to a specified key selector function.
ExceptBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TKey>, Func<TSource,TKey>)	Produces the set difference of two sequences according to a specified key selector function.
First<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)	Returns the first element in a sequence that satisfies a specified condition.
First<TSource>(IEnumerable<TSource>)	Returns the first element of a sequence.
FirstOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>, TSource)	Returns the first element of the sequence that satisfies a condition, or a specified default value if no such element is found.
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.
FirstOrDefault<TSource>(IEnumerable<TSource>, TSource)	Returns the first element of a sequence, or a specified default value if the sequence contains no elements.
FirstOrDefault<TSource>(IEnumerable<TSource>)	Returns the first element of a sequence, or a default value if the sequence contains no elements.
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.
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>(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,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,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,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>(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>(IEnumerable<TSource>, Func<TSource,TKey>)	Groups the elements of a sequence according to a specified key selector function.
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.
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.
Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)	Produces the set intersection of two sequences by using the specified IEqualityComparer<T> to compare values.
Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)	Produces the set intersection of two sequences by using the default equality comparer to compare values.
IntersectBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TKey>, Func<TSource,TKey>, IEqualityComparer<TKey>)	Produces the set intersection of two sequences according to a specified key selector function.
IntersectBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TKey>, Func<TSource,TKey>)	Produces the set intersection of two sequences according to a specified key selector function.
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.
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.
Last<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)	Returns the last element of a sequence that satisfies a specified condition.
Last<TSource>(IEnumerable<TSource>)	Returns the last element of a sequence.
LastOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>, TSource)	Returns the last element of a sequence that satisfies a condition, or a specified default value if no such element is found.
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.
LastOrDefault<TSource>(IEnumerable<TSource>, TSource)	Returns the last element of a sequence, or a specified default value if the sequence contains no elements.
LastOrDefault<TSource>(IEnumerable<TSource>)	Returns the last element of a sequence, or a default value if the sequence contains no elements.
LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)	Returns an Int64 that represents how many elements in a sequence satisfy a condition.
LongCount<TSource>(IEnumerable<TSource>)	Returns an Int64 that represents the total number of elements in a sequence.
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,TResult>(IEnumerable<TSource>, Func<TSource,TResult>)	Invokes a transform function on each element of a generic sequence and returns the maximum resulting value.
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>(IEnumerable<TSource>, IComparer<TSource>)	Returns the maximum value in a generic sequence.
Max<TSource>(IEnumerable<TSource>)	Returns the maximum value in a generic sequence.
MaxBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)	Returns the maximum value in a generic sequence according to a specified key selector function and key comparer.
MaxBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)	Returns the maximum value in a generic sequence according to a specified key selector function.
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,TResult>(IEnumerable<TSource>, Func<TSource,TResult>)	Invokes a transform function on each element of a generic sequence and returns the minimum resulting value.
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>(IEnumerable<TSource>, IComparer<TSource>)	Returns the minimum value in a generic sequence.
Min<TSource>(IEnumerable<TSource>)	Returns the minimum value in a generic sequence.
MinBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)	Returns the minimum value in a generic sequence according to a specified key selector function and key comparer.
MinBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)	Returns the minimum value in a generic sequence according to a specified key selector function.
OfType<TResult>(IEnumerable)	Filters the elements of an IEnumerable based on a specified type.
Order<T>(IEnumerable<T>, IComparer<T>)	Sorts the elements of a sequence in ascending order.
Order<T>(IEnumerable<T>)	Sorts the elements of a sequence in ascending order.
OrderBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)	Sorts the elements of a sequence in ascending order by using a specified comparer.
OrderBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)	Sorts the elements of a sequence in ascending 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.
OrderByDescending<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)	Sorts the elements of a sequence in descending order according to a key.
OrderDescending<T>(IEnumerable<T>, IComparer<T>)	Sorts the elements of a sequence in descending order.
OrderDescending<T>(IEnumerable<T>)	Sorts the elements of a sequence in descending order.
Prepend<TSource>(IEnumerable<TSource>, TSource)	Adds a value to the beginning of the sequence.
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,Int32,TResult>)	Projects each element of a sequence into a new form by incorporating the element's index.
Select<TSource,TResult>(IEnumerable<TSource>, Func<TSource,TResult>)	Projects each element of a sequence into a new form.
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.
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.
SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)	Determines whether two sequences are equal by comparing their elements by using a specified IEqualityComparer<T>.
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.
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.
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.
SingleOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>, TSource)	Returns the only element of a sequence that satisfies a specified condition, or a specified default value if no such element exists; this method throws an exception if more than one element satisfies the condition.
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.
SingleOrDefault<TSource>(IEnumerable<TSource>, TSource)	Returns the only element of a sequence, or a specified 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>)	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.
Skip<TSource>(IEnumerable<TSource>, Int32)	Bypasses a specified number of elements in a sequence and then returns the remaining elements.
SkipLast<TSource>(IEnumerable<TSource>, Int32)	Returns a new enumerable collection that contains the elements from source with the last count elements of the source collection omitted.
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.
Take<TSource>(IEnumerable<TSource>, Range)	Returns a specified range of contiguous elements from a sequence.
TakeLast<TSource>(IEnumerable<TSource>, Int32)	Returns a new enumerable collection that contains the last count elements from source.
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>, IComparer<TKey>)	Performs a subsequent ordering of the elements in a sequence in ascending order by using a specified comparer.
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.
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.
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.
ToArray<TSource>(IEnumerable<TSource>)	Creates an array from a IEnumerable<T>.
ToDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>, IEqualityComparer<TKey>)	Creates a dictionary from an enumeration according to specified key comparer.
ToDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>)	Creates a dictionary from an enumeration according to the default comparer for the key type.
ToDictionary<TKey,TValue>(IEnumerable<ValueTuple<TKey,TValue>>, IEqualityComparer<TKey>)	Creates a dictionary from an enumeration according to specified key equality comparer.
ToDictionary<TKey,TValue>(IEnumerable<ValueTuple<TKey,TValue>>)	Creates a dictionary from an enumeration according to the default comparer for the key type.
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.
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>(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>(IEnumerable<TSource>, Func<TSource,TKey>)	Creates a Dictionary<TKey,TValue> from an IEnumerable<T> according to a specified key selector function.
ToHashSet<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)	Creates a HashSet<T> from an IEnumerable<T> using the comparer to compare keys.
ToHashSet<TSource>(IEnumerable<TSource>)	Creates a HashSet<T> from an IEnumerable<T>.
ToList<TSource>(IEnumerable<TSource>)	Creates a List<T> from an IEnumerable<T>.
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.
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>(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>(IEnumerable<TSource>, Func<TSource,TKey>)	Creates a Lookup<TKey,TElement> from an IEnumerable<T> according to a specified key selector function.
TryGetNonEnumeratedCount<TSource>(IEnumerable<TSource>, Int32)	Attempts to determine the number of elements in a sequence without forcing an enumeration.
Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)	Produces the set union of two sequences by using a specified IEqualityComparer<T>.
Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)	Produces the set union of two sequences by using the default equality comparer.
UnionBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>)	Produces the set union of two sequences according to a specified key selector function.
UnionBy<TSource,TKey>(IEnumerable<TSource>, IEnumerable<TSource>, Func<TSource,TKey>)	Produces the set union of two sequences according to a specified key selector function.
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.
Zip<TFirst,TSecond,TThird>(IEnumerable<TFirst>, IEnumerable<TSecond>, IEnumerable<TThird>)	Produces a sequence of tuples with elements from the three specified sequences.
Zip<TFirst,TSecond>(IEnumerable<TFirst>, IEnumerable<TSecond>)	Produces a sequence of tuples with elements from the two specified sequences.

See also

• Standard Query Operators overview (C#)
• Standard Query Operators overview (Visual Basic)
• Extension Methods (C# Programming Guide)
• Extension Methods (Visual Basic)