C# | Removing first occurrence of object from Collection<T> (original) (raw)

Last Updated : 01 Feb, 2019

Collection<T>.Remove(T) is used to remove the first occurrence of a specific object from the Collection<**T**>.Syntax:

public bool Remove (T item);

Here, item is the object to remove from the Collection<**T**>. The value can be null for reference types.Return Value: True if item is successfully removed, otherwise, False. This method also returns False if item was not found in the original Collection<**T**>. Below given are some examples to understand the implementation in a better way: Example 1:

CSHARP `

// C# code to remove the first // occurrence of a specific object // from 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>();

    // Adding elements in Collection myColl
    myColl.Add("A");
    myColl.Add("B");
    myColl.Add("C");
    myColl.Add("D");
    myColl.Add("E");

    // Displaying the number of elements in myColl
    Console.WriteLine("Count : " + myColl.Count);

    // Displaying the elements in myColl
    foreach(string str in myColl)
    {
        Console.WriteLine(str);
    }

    // Removing the first occurrence of
    // a specific object from the Collection
    myColl.Remove("C");

    // Displaying the number of elements in myColl
    Console.WriteLine("Count : " + myColl.Count);

    // Displaying the elements in myColl
    foreach(string str in myColl)
    {
        Console.WriteLine(str);
    }
}

}

`

Output:

Count : 5 A B C D E Count : 4 A B D E

Example 2:

CSHARP `

// C# code to remove the first // occurrence of a specific object // from 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>();

    // Adding elements in Collection myColl
    myColl.Add(2);
    myColl.Add(3);
    myColl.Add(4);
    myColl.Add(4);
    myColl.Add(5);

    // Displaying the number of elements in myColl
    Console.WriteLine("Count : " + myColl.Count);

    // Displaying the elements in myColl
    foreach(int i in myColl)
    {
        Console.WriteLine(i);
    }

    // Removing the first occurrence of
    // a specific object from the Collection
    myColl.Remove(4);

    // Displaying the number of elements in myColl
    Console.WriteLine("Count : " + myColl.Count);

    // Displaying the elements in myColl
    foreach(int i in myColl)
    {
        Console.WriteLine(i);
    }
}

}

`

Output:

Count : 5 2 3 4 4 5 Count : 4 2 3 4 5

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.remove?view=netframework-4.7.2