VB.Net - Queue

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It represents a first-in, first-out collection of object. It is used when you need a first-in, first-out access of items. When you add an item in the list, it is called enqueue, and when you remove an item, it is called deque

Properties and Methods of the Queue Class

The following table lists some of the commonly used properties of the Queue class:

PropertyDescription
CountGets the number of elements contained in the Queue.

The following table lists some of the commonly used methods of the Queue class:

S.NMethod Name & Purpose
1Public Overridable Sub Clear
Removes all elements from the Queue.
2Public Overridable Function Contains ( obj As Object ) As Boolean
Determines whether an element is in the Queue.
3Public Overridable Function Dequeue As Object
Removes and returns the object at the beginning of the Queue.
4Public Overridable Sub Enqueue ( obj As Object )
Adds an object to the end of the Queue.
5Public Overridable Function ToArray As Object()
Copies the Queue to a new array.
6Public Overridable Sub TrimToSize
Sets the capacity to the actual number of elements in the Queue.

Example:

The following example demonstrates use of Queue:

Module collections
   Sub Main()
      Dim q As Queue = New Queue()
      q.Enqueue("A")
      q.Enqueue("M")
      q.Enqueue("G")
      q.Enqueue("W")
      Console.WriteLine("Current queue: ")
      Dim c As Char
      For Each c In q
          Console.Write(c + " ")
      Next c
      Console.WriteLine()
      q.Enqueue("V")
      q.Enqueue("H")
      Console.WriteLine("Current queue: ")
      For Each c In q
          Console.Write(c + " ")
      Next c
      Console.WriteLine()
      Console.WriteLine("Removing some values ")
      Dim ch As Char
      ch = q.Dequeue()
      Console.WriteLine("The removed value: {0}", ch)
      ch = q.Dequeue()
      Console.WriteLine("The removed value: {0}", ch)
      Console.ReadKey()
   End Sub
End Module

When the above code is compiled and executed, it produces the following result:

Current queue: 
A M G W 
Current queue: 
A M G W V H 
Removing some values
The removed value: A
The removed value: M


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