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C# | Queue<T>.TrimExcess Method with Examples

Last Updated : 01 Feb, 2019
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Queue represents a first-in, first out collection of object. It is used when you need a first-in, first-out access to items. When you add an item in the list, it is called enqueue, and when you remove an item, it is called Dequeue.
Queue<T>.TrimExcess Method is used to set the capacity to the actual number of elements in the Queue<T>, if that number is less than 90 percent of current capacity.

A queue is an unbounded data structure and there is no method available to calculate the capacity of Queue in C#. It is dynamic and depends on the system memory. This method is generally used in memory management of the large queue.
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.


public void TrimExcess ();


  • This method can be used to minimize a collection’s memory overhead if no new elements will be added to the collection.
  • To reset a Queue<T> to its initial state, call the Clear method before calling the TrimExcess method.
  • Trimming an empty Queue<T> sets the capacity of the Queue<T> to the default capacity.

Below given is an example to understand the implementation in a better way:


// C# code to set the capacity to the
// actual number of elements in the Queue
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 elements into Queue
        // To display number of elements in Queue
        // Removing all the elements from Queue
        // using TrimExcess method
        // To display number of elements in Queue




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