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Stack.Push Method

Inserts an object at the top of the Stack.

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

public:
virtual void Push (
	Object^ obj
)
public void Push (
	Object obj
)
public function Push (
	obj : Object
)
Not applicable.

Parameters

obj

The Object to push onto the Stack. The value can be a null reference (Nothing in Visual Basic).

Stack is implemented as a circular buffer.

If Count already equals the capacity, the capacity of the Stack is increased by automatically reallocating the internal array, and the existing elements are copied to the new array before the new element is added.

a null reference (Nothing in Visual Basic) can be pushed onto the Stack as a placeholder, if needed. It occupies a slot in the stack and is treated like any object.

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.

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 namespace System;
using namespace System::Collections;
void PrintValues( IEnumerable^ myCollection, char mySeparator );
int main()
{
   
   // Creates and initializes a new Stack.
   Stack^ myStack = gcnew 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' );
}

void PrintValues( IEnumerable^ myCollection, char mySeparator )
{
   IEnumerator^ myEnum = myCollection->GetEnumerator();
   while ( myEnum->MoveNext() )
   {
      Object^ obj = safe_cast<Object^>(myEnum->Current);
      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
 */

import System.*;
import System.Collections.*;

public class SamplesStack
{

    public static void main(String[] args)
    {
        // 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');
    } //main

    public static void PrintValues(IEnumerable myCollection, char mySeparator)
    {
        IEnumerator l_objmyEnum = myCollection.GetEnumerator();
        while (l_objmyEnum.MoveNext()) {
            Console.Write("{0}{1}", 
                System.Convert.ToString(mySeparator), 
                System.Convert.ToString(l_objmyEnum.get_Current()));
        }
        Console.WriteLine();
    } //PrintValues

} //SamplesStack

/* 
 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
 */

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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