Queue.Enqueue(Object) Method
Definition
Important
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Adds an object to the end of the Queue.
public:
virtual void Enqueue(System::Object ^ obj);
public virtual void Enqueue (object obj);
public virtual void Enqueue (object? obj);
abstract member Enqueue : obj -> unit
override this.Enqueue : obj -> unit
Public Overridable Sub Enqueue (obj As Object)
Parameters
Examples
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 namespace System;
using namespace System::Collections;
void PrintValues( IEnumerable^ myCollection );
int main()
{
// Creates and initializes a new Queue.
Queue^ myQ = gcnew 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 );
}
void PrintValues( IEnumerable^ myCollection )
{
IEnumerator^ myEnum = myCollection->GetEnumerator();
while ( myEnum->MoveNext() )
{
Object^ obj = safe_cast<Object^>(myEnum->Current);
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
*/
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
*/
Imports System.Collections
Public Class SamplesQueue
Public Shared Sub Main()
' Creates and initializes a new Queue.
Dim myQ As 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) {0}", myQ.Dequeue())
' Displays the Queue.
Console.Write("Queue values:")
PrintValues(myQ)
' Removes another element from the Queue.
Console.WriteLine("(Dequeue) {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) {0}", myQ.Peek())
' Displays the Queue.
Console.Write("Queue values:")
PrintValues(myQ)
End Sub
Public Shared Sub PrintValues(myCollection As IEnumerable)
Dim obj As [Object]
For Each obj In myCollection
Console.Write(" {0}", obj)
Next obj
Console.WriteLine()
End Sub
End Class
' 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
Remarks
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.