Stack.Pop Method

Removes and returns the object at the top of the Stack.

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

public virtual Object Pop()

Return Value

Type: System.Object
The Object removed from the top of the Stack.

ExceptionCondition
InvalidOperationException

The Stack is empty.

This method is similar to the Peek method, but Peek does not modify the Stack.

null can be pushed onto the Stack as a placeholder, if needed. To distinguish between a null value and the end of the stack, check the Count property or catch the InvalidOperationException, which is thrown when the Stack is empty.

Stack is implemented as a circular buffer. This method is an O(1) operation.

The following example shows how to add elements to the Stack, remove elements from the Stack, or view the element at the top of the Stack.

 using System;
 using System.Collections;
 public class SamplesStack  {

    public static void Main()  {

       // Creates and initializes a new Stack.
       Stack myStack = new Stack();
       myStack.Push( "The" );
       myStack.Push( "quick" );
       myStack.Push( "brown" );
       myStack.Push( "fox" );

       // Displays the Stack.
       Console.Write( "Stack values:" );
       PrintValues( myStack, '\t' );

       // Removes an element from the Stack.
       Console.WriteLine( "(Pop)\t\t{0}", myStack.Pop() );

       // Displays the Stack.
       Console.Write( "Stack values:" );
       PrintValues( myStack, '\t' );

       // Removes another element from the Stack.
       Console.WriteLine( "(Pop)\t\t{0}", myStack.Pop() );

       // Displays the Stack.
       Console.Write( "Stack values:" );
       PrintValues( myStack, '\t' );

       // Views the first element in the Stack but does not remove it.
       Console.WriteLine( "(Peek)\t\t{0}", myStack.Peek() );

       // Displays the Stack.
       Console.Write( "Stack values:" );
       PrintValues( myStack, '\t' );
    }


    public static void PrintValues( IEnumerable myCollection, char mySeparator )  {
       foreach ( Object obj in myCollection )
          Console.Write( "{0}{1}", mySeparator, obj );
       Console.WriteLine();
    }

 }


 /* 
 This code produces the following output.

 Stack values:    fox    brown    quick    The
 (Pop)        fox
 Stack values:    brown    quick    The
 (Pop)        brown
 Stack values:    quick    The
 (Peek)        quick
 Stack values:    quick    The
 */

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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