C# | Check if an element is in the Collection<T>

Last Updated : 01 Feb, 2019

Collection<T>.Contains(T) method is used to determine whether an element is in the Collection<T>.

Syntax:

public bool Contains (T item);

Here, item is the object to locate in the Collection<T>. The value can be null for reference types.

Return Value: This method return True if item is found in the Collection<T>, otherwise, False.

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

Example 1:

// C# code to check if an 
// element is in the Collection 
using System; 
using System.Collections.Generic; 
using System.Collections.ObjectModel; 
  
class GFG { 
  
    // Driver code 
    public static void Main() 
    { 
        // Creating a collection of strings 
        Collection<string> myColl = new Collection<string>(); 
  
        myColl.Add("A"); 
        myColl.Add("B"); 
        myColl.Add("C"); 
        myColl.Add("D"); 
        myColl.Add("E"); 
  
        // Checking if an element is in the Collection 
        // The function returns "True" if the 
        // item is present in Collection 
        // else returns "False" 
        Console.WriteLine(myColl.Contains("A")); 
    } 
} 

Output:

True

Example 2:

// C# code to check if an 
// element is in the Collection 
using System; 
using System.Collections.Generic; 
using System.Collections.ObjectModel; 
  
class GFG { 
  
    // Driver code 
    public static void Main() 
    { 
        // Creating a collection of ints 
        Collection<int> myColl = new Collection<int>(); 
  
        myColl.Add(2); 
        myColl.Add(3); 
        myColl.Add(4); 
        myColl.Add(5); 
  
        // Checking if an element is in the Collection 
        // The function returns "True" if the 
        // item is present in Collection 
        // else returns "False" 
        Console.WriteLine(myColl.Contains(6)); 
    } 
} 

Output:

False

Note: This method performs a linear search. Therefore, this method is an O(n) operation, where n is Count.

Reference:

https://docs.microsoft.com/en-us/dotnet/api/system.collections.objectmodel.collection-1.contains?view=netframework-4.7.2

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