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Stack contains() method in C#

The Contains() function in C# is a vital component of the Stack class of the .NET Framework to quickly ascertain if a certain element is included in a stack data structure. When you need to confirm whether a certain item is present in the stack before taking more action, this approach comes in convenient. Contains() is a function that, whenever used, returns a boolean value: false if the specified element is not present in the stack while it returns true otherwise. It is an easy-to-use solution for developers to organize data in a Last-In-First-Out (LIFO) fashion because of its simplicity and efficacy. C# programmers may easily improve the accuracy and dependability associated with their stack-based algorithms and applications by utilizing this technique.

A stack can be represented in C# by the Stack class, where T is the type of elements the stack contains. The Contains() method constitutes a single of the multiple techniques this class offers for working alongside the stack.

Stack contains() method in C#

Presenting the Contains() Technique

You can utilize the Contains() method to ascertain if a certain element has been placed on the top of the stack or not. It gives back an empty boolean response that indicates if the given element has been included or not.


It has the following syntax:

How does Contains() method Operates?

The key components in the stack have been repeated over from the top (the most recently added element) to the bottom (the least recently added element) when the Contains() function is called on a stack instance. It uses the equality comparison of type T to compare each element with the given item. The method returns false otherwise and returns positive if a matching element is discovered.

C# Program:

Let us take an example to illustrate the stack contains() method in C#.


Stack contains 20: True
Stack contains 40: False


  • In this example, we import the Collections.Generic namespace to utilize the Stack<T> class.
  • Next, we create a new stack called stack to store integers as well.
  • Using the Push() function, we push three numbers (10, 20, and 30) into the stack.
  • After that, we utilize the Contains() function to determine if the components 20 and 40 are present in the stack.
  • Lastly, we publish the results, indicating the degree to which the given components exist in the stack.

Performance-Related Issues

The efficiency ramifications of utilizing the Contains() function must be considered, particularly for big stacks. O(n), where n is the number of elements in the stack, is the temporal complexity of the technique. This is because it must go throughout every element in the stack of elements until it either encounters a match or runs out of space.


In conclusion, the C# Contains() function offers a practical means of determining if an element within a stack exists. It has a straightforward syntax and yields a boolean value that indicates whether or not the given element is in the stack. However, as a result of its linear temporal complexity, it's important to take the performance implications into account, particularly for more expansive stacks.

Application logic may be enhanced more robust and dependable by effectively validating the existence of ingredients within a stack with the help of the Contains() function.

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