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C# | Check if an element is in the Queue
  • Last Updated : 01 Feb, 2019

Queue 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. Queue.Contains(T) Method is used to check whether an element is in the Queue.

Properties:

  • Enqueue adds an element to the end of the Queue.
  • Dequeue removes the oldest element from the start of the Queue.
  • Peek returns the oldest element that is at the start of the Queue but does not remove it from the Queue.
  • 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 by reallocating the internal array.
  • Queue accepts null as a valid value for reference types and allows duplicate elements.

Syntax:

public virtual bool Contains(object obj);

Return Value: The function returns True if the element exists in the Queue and returns False if the element doesn’t exist in the Queue.

Below given are some examples to understand the implementation in a better way:



Example 1:




// C# code to Check if a Queue
// contains an element
using System;
using System.Collections.Generic;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a Queue of Integers
        Queue<int> myQueue = new Queue<int>();
  
        // Inserting the elements into the Queue
        myQueue.Enqueue(5);
        myQueue.Enqueue(10);
        myQueue.Enqueue(15);
        myQueue.Enqueue(20);
        myQueue.Enqueue(25);
  
        // Checking whether the element is
        // present in the Queue or not
        // The function returns True if the
        // element is present in the Queue, else
        // returns False
        Console.WriteLine(myQueue.Contains(7));
    }
}
Output:
False

Example 2:




// C# code to Check if a Queue
// contains an element
using System;
using System.Collections.Generic;
  
class GFG {
  
    // Driver code
    public static void Main()
    {
  
        // Creating a Queue of strings
        Queue<string> myQueue = new Queue<string>();
  
        // Inserting the elements into the Queue
        myQueue.Enqueue("Geeks");
        myQueue.Enqueue("Geeks Classes");
        myQueue.Enqueue("Noida");
        myQueue.Enqueue("Data Structures");
        myQueue.Enqueue("GeeksforGeeks");
  
        // Checking whether the element is
        // present in the Queue or not
        // The function returns True if the
        // element is present in the Queue, else
        // returns False
        Console.WriteLine(myQueue.Contains("GeeksforGeeks"));
    }
}
Output:
True

Reference:




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