Stack<T> Class (System.Collections.Generic)

Overview

The Stack<T> class represents a last-in‑first-out (LIFO) collection of objects. It provides methods to push and pop items, as well as to peek at the top item without removing it.

public class Stack<T> : System.Collections.Generic.IEnumerable<T>, System.Collections.ICollection, System.Collections.IEnumerable, System.Collections.Generic.IReadOnlyCollection<T>

using System;
using System.Collections.Generic;

class Program
{
    static void Main()
    {
        var stack = new Stack<int>();
        stack.Push(10);
        stack.Push(20);
        Console.WriteLine(stack.Peek()); // 20
        Console.WriteLine(stack.Pop());  // 20
        Console.WriteLine(stack.Count); // 1
    }
}

Type Parameters

Parameter	Description
`T`	The type of elements in the stack.

Properties

Name	Type	Description
`Count`	int	Gets the number of elements contained in the `Stack<T>`.
`IsSynchronized`	bool	Indicates whether access to the `Stack<T>` is synchronized (thread safe). Always false.
`SyncRoot`	object	Object used to synchronize access to the `Stack<T>`. Always returns the current instance.

Methods

Push

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

public void Push(T item)

Pop

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

public T Pop()

Peek

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

public T Peek()

Clear

Removes all objects from the Stack<T>.

public void Clear()

Contains

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

public bool Contains(T item)

ToArray

Copies the Stack<T> to a new array.

public T[] ToArray()

CopyTo

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

public void CopyTo(T[] array, int arrayIndex)

GetEnumerator

Returns an enumerator that iterates through the stack.

public IEnumerator<T> GetEnumerator()

Remarks

The Stack<T> class is sealed; therefore it cannot be inherited. It is not thread‑safe. To enable thread safety, you must synchronize access manually.