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Queue.Enqueue Method

Adds an object to the end of the Queue.

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

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

Parameters

obj

The object to add to the Queue. The value can be a null reference (Nothing in Visual Basic).

The capacity of a Queue is the number of elements the Queue can hold. As elements are added to a Queue, the capacity is automatically increased as required through reallocation. The capacity can be decreased by calling TrimToSize.

The growth factor is the number by which the current capacity is multiplied when a greater capacity is required. The growth factor is determined when the Queue is constructed. The capacity of the Queue will always increase by a minimum value, regardless of the growth factor; a growth factor of 1.0 will not prevent the Queue from increasing in size.

If Count is less than the capacity of the internal array, this method is an O(1) operation. If the internal array needs to be reallocated to accommodate the new element, this method becomes an O(n) operation, where n is Count.

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

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

   public static void Main()  {

      // Creates and initializes a new Queue.
      Queue myQ = new Queue();
      myQ.Enqueue( "The" );
      myQ.Enqueue( "quick" );
      myQ.Enqueue( "brown" );
      myQ.Enqueue( "fox" );

      // Displays the Queue.
      Console.Write( "Queue values:" );
      PrintValues( myQ );

      // Removes an element from the Queue.
      Console.WriteLine( "(Dequeue)\t{0}", myQ.Dequeue() );

      // Displays the Queue.
      Console.Write( "Queue values:" );
      PrintValues( myQ );

      // Removes another element from the Queue.
      Console.WriteLine( "(Dequeue)\t{0}", myQ.Dequeue() );

      // Displays the Queue.
      Console.Write( "Queue values:" );
      PrintValues( myQ );

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

      // Displays the Queue.
      Console.Write( "Queue values:" );
      PrintValues( myQ );
   }

   public static void PrintValues( IEnumerable myCollection )  {
      foreach ( Object obj in myCollection )
         Console.Write( "    {0}", obj );
      Console.WriteLine();
   }
}
/* 
This code produces the following output.

Queue values:    The    quick    brown    fox
(Dequeue)       The
Queue values:    quick    brown    fox
(Dequeue)       quick
Queue values:    brown    fox
(Peek)          brown
Queue values:    brown    fox

*/ 

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

public class SamplesQueue
{
    public static void main(String[] args)
    {
        // Creates and initializes a new Queue.
        Queue myQ =  new Queue();
        myQ.Enqueue("The");
        myQ.Enqueue("quick");
        myQ.Enqueue("brown");
        myQ.Enqueue("fox");

        // Displays the Queue.
        Console.Write("Queue values:");
        PrintValues(myQ);

        // Removes an element from the Queue.
        Console.WriteLine("(Dequeue)\t{0}", myQ.Dequeue());

        // Displays the Queue.
        Console.Write("Queue values:");
        PrintValues(myQ);

        // Removes another element from the Queue.
        Console.WriteLine("(Dequeue)\t{0}", myQ.Dequeue());

        // Displays the Queue.
        Console.Write("Queue values:");
        PrintValues(myQ);

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

        // Displays the Queue.
        Console.Write("Queue values:");
        PrintValues(myQ);
    } //main

    public static void PrintValues(IEnumerable myCollection)
    {
        IEnumerator e = myCollection.GetEnumerator();
        while (e.MoveNext()) {
            Object obj = e.get_Current();
            Console.Write("    {0}", obj);
        }
        Console.WriteLine();
    } //PrintValues
} //SamplesQueue

/* 
 This code produces the following output.
 
 Queue values:    The    quick    brown    fox
 (Dequeue)       The
 Queue values:    quick    brown    fox
 (Dequeue)       quick
 Queue values:    brown    fox
 (Peek)          brown
 Queue values:    brown    fox
 */

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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