Stack<T> Class

Definition

Represents a variable size last-in-first-out (LIFO) collection of instances of the same specified type.

[System.Runtime.InteropServices.ComVisible(false)]
public class Stack<T> : System.Collections.Generic.IEnumerable<T>, System.Collections.Generic.IReadOnlyCollection<T>, System.Collections.ICollection
Type Parameters
T

Specifies the type of elements in the stack.

Inheritance
Stack<T>
Attributes
Implements

Inherited Members

System.Object

Examples

The following code example demonstrates several methods of the Stack<T> generic class. The code example creates a stack of strings with default capacity and uses the Push method to push five strings onto the stack. The elements of the stack are enumerated, which does not change the state of the stack. The Pop method is used to pop the first string off the stack. The Peek method is used to look at the next item on the stack, and then the Pop method is used to pop it off.

The ToArray method is used to create an array and copy the stack elements to it, then the array is passed to the Stack<T> constructor that takes IEnumerable<T>, creating a copy of the stack with the order of the elements reversed. The elements of the copy are displayed.

An array twice the size of the stack is created, and the CopyTo method is used to copy the array elements beginning at the middle of the array. The Stack<T> constructor is used again to create a copy of the stack with the order of elements reversed; thus, the three null elements are at the end.

The Contains method is used to show that the string "four" is in the first copy of the stack, after which the Clear method clears the copy and the Count property shows that the stack is empty.

using System;
using System.Collections.Generic;

class Example
{
    public static void Main()
    {
        Stack<string> numbers = new Stack<string>();
        numbers.Push("one");
        numbers.Push("two");
        numbers.Push("three");
        numbers.Push("four");
        numbers.Push("five");

        // A stack can be enumerated without disturbing its contents.
        foreach( string number in numbers )
        {
            Console.WriteLine(number);
        }

        Console.WriteLine("\nPopping '{0}'", numbers.Pop());
        Console.WriteLine("Peek at next item to destack: {0}", 
            numbers.Peek());
        Console.WriteLine("Popping '{0}'", numbers.Pop());

        // Create a copy of the stack, using the ToArray method and the
        // constructor that accepts an IEnumerable<T>.
        Stack<string> stack2 = new Stack<string>(numbers.ToArray());

        Console.WriteLine("\nContents of the first copy:");
        foreach( string number in stack2 )
        {
            Console.WriteLine(number);
        }
        
        // Create an array twice the size of the stack and copy the
        // elements of the stack, starting at the middle of the 
        // array. 
        string[] array2 = new string[numbers.Count * 2];
        numbers.CopyTo(array2, numbers.Count);
        
        // Create a second stack, using the constructor that accepts an
        // IEnumerable(Of T).
        Stack<string> stack3 = new Stack<string>(array2);

        Console.WriteLine("\nContents of the second copy, with duplicates and nulls:");
        foreach( string number in stack3 )
        {
            Console.WriteLine(number);
        }

        Console.WriteLine("\nstack2.Contains(\"four\") = {0}", 
            stack2.Contains("four"));

        Console.WriteLine("\nstack2.Clear()");
        stack2.Clear();
        Console.WriteLine("\nstack2.Count = {0}", stack2.Count);
    }
}

/* This code example produces the following output:

five
four
three
two
one

Popping 'five'
Peek at next item to destack: four
Popping 'four'

Contents of the first copy:
one
two
three

Contents of the second copy, with duplicates and nulls:
one
two
three




stack2.Contains("four") = False

stack2.Clear()

stack2.Count = 0
 */
Imports System
Imports System.Collections.Generic

Module Example

    Sub Main

        Dim numbers As New Stack(Of String)
        numbers.Push("one")
        numbers.Push("two")
        numbers.Push("three")
        numbers.Push("four")
        numbers.Push("five")

        ' A stack can be enumerated without disturbing its contents.
        For Each number As String In numbers
            Console.WriteLine(number)
        Next

        Console.WriteLine(vbLf & "Popping '{0}'", numbers.Pop())
        Console.WriteLine("Peek at next item to pop: {0}", _
            numbers.Peek())    
        Console.WriteLine("Popping '{0}'", numbers.Pop())

        ' Create another stack, using the ToArray method and the
        ' constructor that accepts an IEnumerable(Of T). Note that
        ' the order of items on the new stack is reversed.
        Dim stack2 As New Stack(Of String)(numbers.ToArray())

        Console.WriteLine(vbLf & "Contents of the first copy:")
        For Each number As String In stack2
            Console.WriteLine(number)
        Next
        
        ' Create an array twice the size of the stack, compensating
        ' for the fact that Visual Basic allocates an extra array 
        ' element. Copy the elements of the stack, starting at the
        ' middle of the array. 
        Dim array2((numbers.Count * 2) - 1) As String
        numbers.CopyTo(array2, numbers.Count)
        
        ' Create a second stack, using the constructor that accepts an
        ' IEnumerable(Of T). The elements are reversed, with the null
        ' elements appearing at the end of the stack when enumerated.
        Dim stack3 As New Stack(Of String)(array2)

        Console.WriteLine(vbLf & _
            "Contents of the second copy, with duplicates and nulls:")
        For Each number As String In stack3
            Console.WriteLine(number)
        Next

        Console.WriteLine(vbLf & "stack2.Contains(""four"") = {0}", _
            stack2.Contains("four"))

        Console.WriteLine(vbLf & "stack2.Clear()")
        stack2.Clear()
        Console.WriteLine(vbLf & "stack2.Count = {0}", _
            stack2.Count)
    End Sub
End Module

' This code example produces the following output:
'
'five
'four
'three
'two
'one
'
'Popping 'five'
'Peek at next item to pop: four
'Popping 'four'
'
'Contents of the first copy:
'one
'two
'three
'
'Contents of the second copy, with duplicates and nulls:
'one
'two
'three
'
'
'
'
'stack2.Contains("four") = False
'
'stack2.Clear()
'
'stack2.Count = 0

Remarks

Stack<T> is implemented as an array.

Stacks and queues are useful when you need temporary storage for information; that is, when you might want to discard an element after retrieving its value. Use Queue<T> if you need to access the information in the same order that it is stored in the collection. Use Stack<T> if you need to access the information in reverse order.

Use the ConcurrentStack<T> and ConcurrentQueue<T> types when you need to access the collection from multiple threads concurrently.

A common use for Stack<T> is to preserve variable states during calls to other procedures.

Three main operations can be performed on a Stack<T> and its elements:

  • Push inserts an element at the top of the Stack.

  • Pop removes an element from the top of the Stack<T>.

  • Peek returns an element that is at the top of the Stack<T> but does not remove it from the Stack<T>.

The capacity of a Stack<T> is the number of elements the Stack<T> can hold. As elements are added to a Stack<T>, the capacity is automatically increased as required by reallocating the internal array. The capacity can be decreased by calling TrimExcess.

If Count is less than the capacity of the stack, Push is an O(1) operation. If the capacity needs to be increased to accommodate the new element, Push becomes an O(n) operation, where n is Count. Pop is an O(1) operation.

Stack<T> accepts null as a valid value for reference types and allows duplicate elements.

Constructors

Stack<T>()

Initializes a new instance of the Stack<T> class that is empty and has the default initial capacity.

Stack<T>(IEnumerable<T>)

Initializes a new instance of the Stack<T> class that contains elements copied from the specified collection and has sufficient capacity to accommodate the number of elements copied.

Stack<T>(Int32)

Initializes a new instance of the Stack<T> class that is empty and has the specified initial capacity or the default initial capacity, whichever is greater.

Properties

Count

Gets the number of elements contained in the Stack<T>.

Methods

Clear()

Removes all objects from the Stack<T>.

Contains(T)

Determines whether an element is in the Stack<T>.

CopyTo(T[], Int32)

Copies the Stack<T> to an existing one-dimensional Array, starting at the specified array index.

GetEnumerator()

Returns an enumerator for the Stack<T>.

Peek()

Returns the object at the top of the Stack<T> without removing it.

Pop()

Removes and returns the object at the top of the Stack<T>.

Push(T)

Inserts an object at the top of the Stack<T>.

ToArray()

Copies the Stack<T> to a new array.

TrimExcess()

Sets the capacity to the actual number of elements in the Stack<T>, if that number is less than 90 percent of current capacity.

TryPeek(T)
TryPop(T)

Explicit Interface Implementations

IEnumerable<T>.GetEnumerator()

Returns an enumerator that iterates through the collection.

ICollection.CopyTo(Array, Int32)

Copies the elements of the ICollection to an Array, starting at a particular Array index.

ICollection.IsSynchronized

Gets a value indicating whether access to the ICollection is synchronized (thread safe).

ICollection.SyncRoot

Gets an object that can be used to synchronize access to the ICollection.

IEnumerable.GetEnumerator()

Returns an enumerator that iterates through a collection.

Extension Methods

ToImmutableArray<TSource>(IEnumerable<TSource>)
ToImmutableDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)
ToImmutableDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>)
ToImmutableDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>)
ToImmutableDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>, IEqualityComparer<TKey>)
ToImmutableDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>, IEqualityComparer<TKey>, IEqualityComparer<TValue>)
ToImmutableDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>)
ToImmutableDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>, IEqualityComparer<TKey>)
ToImmutableDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>, IEqualityComparer<TKey>, IEqualityComparer<TValue>)
ToImmutableHashSet<TSource>(IEnumerable<TSource>)
ToImmutableHashSet<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)
ToImmutableList<TSource>(IEnumerable<TSource>)
ToImmutableSortedDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>)
ToImmutableSortedDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>, IComparer<TKey>)
ToImmutableSortedDictionary<TKey,TValue>(IEnumerable<KeyValuePair<TKey,TValue>>, IComparer<TKey>, IEqualityComparer<TValue>)
ToImmutableSortedDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>)
ToImmutableSortedDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>, IComparer<TKey>)
ToImmutableSortedDictionary<TSource,TKey,TValue>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TValue>, IComparer<TKey>, IEqualityComparer<TValue>)
ToImmutableSortedSet<TSource>(IEnumerable<TSource>)
ToImmutableSortedSet<TSource>(IEnumerable<TSource>, IComparer<TSource>)
CopyToDataTable<T>(IEnumerable<T>)
CopyToDataTable<T>(IEnumerable<T>, DataTable, LoadOption)
CopyToDataTable<T>(IEnumerable<T>, DataTable, LoadOption, FillErrorEventHandler)
Aggregate<TSource>(IEnumerable<TSource>, Func<TSource,TSource,TSource>)
Aggregate<TSource,TAccumulate>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>)
Aggregate<TSource,TAccumulate,TResult>(IEnumerable<TSource>, TAccumulate, Func<TAccumulate,TSource,TAccumulate>, Func<TAccumulate,TResult>)
All<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
Any<TSource>(IEnumerable<TSource>)
Any<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
Append<TSource>(IEnumerable<TSource>, TSource)
AsEnumerable<TSource>(IEnumerable<TSource>)
Average(IEnumerable<Decimal>)
Average(IEnumerable<Double>)
Average(IEnumerable<Int32>)
Average(IEnumerable<Int64>)
Average(IEnumerable<Nullable<Decimal>>)
Average(IEnumerable<Nullable<Double>>)
Average(IEnumerable<Nullable<Int32>>)
Average(IEnumerable<Nullable<Int64>>)
Average(IEnumerable<Nullable<Single>>)
Average(IEnumerable<Single>)
Average<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>)
Average<TSource>(IEnumerable<TSource>, Func<TSource,Double>)
Average<TSource>(IEnumerable<TSource>, Func<TSource,Int32>)
Average<TSource>(IEnumerable<TSource>, Func<TSource,Int64>)
Average<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>)
Average<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>)
Average<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>)
Average<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>)
Average<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>)
Average<TSource>(IEnumerable<TSource>, Func<TSource,Single>)
Cast<TResult>(IEnumerable)
Concat<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)
Contains<TSource>(IEnumerable<TSource>, TSource)
Contains<TSource>(IEnumerable<TSource>, TSource, IEqualityComparer<TSource>)
Count<TSource>(IEnumerable<TSource>)
Count<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
DefaultIfEmpty<TSource>(IEnumerable<TSource>)
DefaultIfEmpty<TSource>(IEnumerable<TSource>, TSource)
Distinct<TSource>(IEnumerable<TSource>)
Distinct<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)
ElementAt<TSource>(IEnumerable<TSource>, Int32)
ElementAtOrDefault<TSource>(IEnumerable<TSource>, Int32)
Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)
Except<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)
First<TSource>(IEnumerable<TSource>)
First<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
FirstOrDefault<TSource>(IEnumerable<TSource>)
FirstOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
GroupBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)
GroupBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>)
GroupBy<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>)
GroupBy<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>)
GroupBy<TSource,TKey,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TKey,IEnumerable<TSource>,TResult>)
GroupBy<TSource,TKey,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TKey,IEnumerable<TSource>,TResult>, IEqualityComparer<TKey>)
GroupBy<TSource,TKey,TElement,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, Func<TKey,IEnumerable<TElement>,TResult>)
GroupBy<TSource,TKey,TElement,TResult>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, Func<TKey,IEnumerable<TElement>,TResult>, IEqualityComparer<TKey>)
GroupJoin<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,IEnumerable<TInner>,TResult>)
GroupJoin<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,IEnumerable<TInner>,TResult>, IEqualityComparer<TKey>)
Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)
Intersect<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)
Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>)
Join<TOuter,TInner,TKey,TResult>(IEnumerable<TOuter>, IEnumerable<TInner>, Func<TOuter,TKey>, Func<TInner,TKey>, Func<TOuter,TInner,TResult>, IEqualityComparer<TKey>)
Last<TSource>(IEnumerable<TSource>)
Last<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
LastOrDefault<TSource>(IEnumerable<TSource>)
LastOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
LongCount<TSource>(IEnumerable<TSource>)
LongCount<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
Max(IEnumerable<Decimal>)
Max(IEnumerable<Double>)
Max(IEnumerable<Int32>)
Max(IEnumerable<Int64>)
Max(IEnumerable<Nullable<Decimal>>)
Max(IEnumerable<Nullable<Double>>)
Max(IEnumerable<Nullable<Int32>>)
Max(IEnumerable<Nullable<Int64>>)
Max(IEnumerable<Nullable<Single>>)
Max(IEnumerable<Single>)
Max<TSource>(IEnumerable<TSource>)
Max<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>)
Max<TSource>(IEnumerable<TSource>, Func<TSource,Double>)
Max<TSource>(IEnumerable<TSource>, Func<TSource,Int32>)
Max<TSource>(IEnumerable<TSource>, Func<TSource,Int64>)
Max<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>)
Max<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>)
Max<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>)
Max<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>)
Max<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>)
Max<TSource>(IEnumerable<TSource>, Func<TSource,Single>)
Max<TSource,TResult>(IEnumerable<TSource>, Func<TSource,TResult>)
Min(IEnumerable<Decimal>)
Min(IEnumerable<Double>)
Min(IEnumerable<Int32>)
Min(IEnumerable<Int64>)
Min(IEnumerable<Nullable<Decimal>>)
Min(IEnumerable<Nullable<Double>>)
Min(IEnumerable<Nullable<Int32>>)
Min(IEnumerable<Nullable<Int64>>)
Min(IEnumerable<Nullable<Single>>)
Min(IEnumerable<Single>)
Min<TSource>(IEnumerable<TSource>)
Min<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>)
Min<TSource>(IEnumerable<TSource>, Func<TSource,Double>)
Min<TSource>(IEnumerable<TSource>, Func<TSource,Int32>)
Min<TSource>(IEnumerable<TSource>, Func<TSource,Int64>)
Min<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>)
Min<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>)
Min<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>)
Min<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>)
Min<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>)
Min<TSource>(IEnumerable<TSource>, Func<TSource,Single>)
Min<TSource,TResult>(IEnumerable<TSource>, Func<TSource,TResult>)
OfType<TResult>(IEnumerable)
OrderBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)
OrderBy<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)
OrderByDescending<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)
OrderByDescending<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IComparer<TKey>)
Prepend<TSource>(IEnumerable<TSource>, TSource)
Reverse<TSource>(IEnumerable<TSource>)
Select<TSource,TResult>(IEnumerable<TSource>, Func<TSource,TResult>)
Select<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,TResult>)
SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TResult>>)
SelectMany<TSource,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TResult>>)
SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>)
SelectMany<TSource,TCollection,TResult>(IEnumerable<TSource>, Func<TSource,Int32,IEnumerable<TCollection>>, Func<TSource,TCollection,TResult>)
SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)
SequenceEqual<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)
Single<TSource>(IEnumerable<TSource>)
Single<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
SingleOrDefault<TSource>(IEnumerable<TSource>)
SingleOrDefault<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
Skip<TSource>(IEnumerable<TSource>, Int32)
SkipLast<TSource>(IEnumerable<TSource>, Int32)
SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
SkipWhile<TSource>(IEnumerable<TSource>, Func<TSource,Int32,Boolean>)
Sum(IEnumerable<Decimal>)
Sum(IEnumerable<Double>)
Sum(IEnumerable<Int32>)
Sum(IEnumerable<Int64>)
Sum(IEnumerable<Nullable<Decimal>>)
Sum(IEnumerable<Nullable<Double>>)
Sum(IEnumerable<Nullable<Int32>>)
Sum(IEnumerable<Nullable<Int64>>)
Sum(IEnumerable<Nullable<Single>>)
Sum(IEnumerable<Single>)
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Decimal>)
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Double>)
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int32>)
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Int64>)
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Decimal>>)
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Double>>)
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int32>>)
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Int64>>)
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Nullable<Single>>)
Sum<TSource>(IEnumerable<TSource>, Func<TSource,Single>)
Take<TSource>(IEnumerable<TSource>, Int32)
TakeLast<TSource>(IEnumerable<TSource>, Int32)
TakeWhile<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
TakeWhile<TSource>(IEnumerable<TSource>, Func<TSource,Int32,Boolean>)
ToArray<TSource>(IEnumerable<TSource>)
ToDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)
ToDictionary<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>)
ToDictionary<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>)
ToDictionary<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>)
ToHashSet<TSource>(IEnumerable<TSource>)
ToHashSet<TSource>(IEnumerable<TSource>, IEqualityComparer<TSource>)
ToList<TSource>(IEnumerable<TSource>)
ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>)
ToLookup<TSource,TKey>(IEnumerable<TSource>, Func<TSource,TKey>, IEqualityComparer<TKey>)
ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>)
ToLookup<TSource,TKey,TElement>(IEnumerable<TSource>, Func<TSource,TKey>, Func<TSource,TElement>, IEqualityComparer<TKey>)
Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>)
Union<TSource>(IEnumerable<TSource>, IEnumerable<TSource>, IEqualityComparer<TSource>)
Where<TSource>(IEnumerable<TSource>, Func<TSource,Boolean>)
Where<TSource>(IEnumerable<TSource>, Func<TSource,Int32,Boolean>)
Zip<TFirst,TSecond,TResult>(IEnumerable<TFirst>, IEnumerable<TSecond>, Func<TFirst,TSecond,TResult>)
AsParallel(IEnumerable)
AsParallel<TSource>(IEnumerable<TSource>)
AsQueryable(IEnumerable)
AsQueryable<TElement>(IEnumerable<TElement>)
Ancestors<T>(IEnumerable<T>)
Ancestors<T>(IEnumerable<T>, XName)
AncestorsAndSelf(IEnumerable<XElement>)
AncestorsAndSelf(IEnumerable<XElement>, XName)
Attributes(IEnumerable<XElement>)
Attributes(IEnumerable<XElement>, XName)
DescendantNodes<T>(IEnumerable<T>)
DescendantNodesAndSelf(IEnumerable<XElement>)
Descendants<T>(IEnumerable<T>)
Descendants<T>(IEnumerable<T>, XName)
DescendantsAndSelf(IEnumerable<XElement>)
DescendantsAndSelf(IEnumerable<XElement>, XName)
Elements<T>(IEnumerable<T>)
Elements<T>(IEnumerable<T>, XName)
InDocumentOrder<T>(IEnumerable<T>)
Nodes<T>(IEnumerable<T>)
Remove(IEnumerable<XAttribute>)
Remove<T>(IEnumerable<T>)

Thread Safety

Public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

A Stack<T> can support multiple readers concurrently, as long as the collection is not modified. Even so, enumerating through a collection is intrinsically not a thread-safe procedure. To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.