C# / .NET - count number of element occurrences in List

In this article, we would like to show you how to count number of element occurrences in List in C#.

Quick solution:

List<string> myList = new List<string> { "A", "B", "B", "C", "C", "C" };

var occurrences = myList.GroupBy(x => x).ToDictionary(y => y.Key, z => z.Count());

// Output:
// [A, 1]
// [B, 2]
// [C, 3]

Practical example

In this example, we use methods from System.Linq to group items into key / value pairs, where key is the item name and value is the number of occurrences.

using System;
using System.Linq;
using System.Collections.Generic;

public class Program
{
    public static void Main()
    {
        List<string> myList = new List<string> { "A", "B", "B", "C", "C", "C" };

        var occurrences = myList.GroupBy(x => x).ToDictionary(y => y.Key, z => z.Count());

        foreach (var item in occurrences)
            Console.WriteLine(item);
    }
}

Output:

Output:
[A, 1]
[B, 2]
[C, 3]

References

1. Enumerable.GroupBy Method (System.Linq) | Microsoft Docs
2. Enumerable.ToDictionary Method (System.Linq) | Microsoft Docs
3. Enumerable.Count Method (System.Linq) | Microsoft Docs