count duplicates in a collection in csharp

To count duplicates in a collection in C#, you can use LINQ to group the elements by their value, and then count the number of items in each group greater than one. Here's an example using a List<string>:


main.cs
List<string> list = new List<string> { "apple", "banana", "cherry", "apple", "date", "banana", "apple" };

var duplicates = list
    .GroupBy(s => s) // group by value
    .Where(g => g.Count() > 1) // select groups with count greater than 1
    .Select(g => new { Value = g.Key, Count = g.Count() }); // select value and count

foreach (var duplicate in duplicates)
{
    Console.WriteLine($"Value: {duplicate.Value}, Count: {duplicate.Count}");
}
449 chars
12 lines

This will output:


main.cs
Value: apple, Count: 3
Value: banana, Count: 2
47 chars
3 lines

This approach can be used with any type of collection and any type of element, as long as the element type implements Equals and GetHashCode correctly.

similar csharp code snippets

normalize a collection of objects in csharp

count the digits in an int in csharp

find duplicates in a list in csharp

insert an element into an array at a specific index in csharp

find the index of an element in an array in csharp

remove an element from the beginning of an array in csharp

remove an element from the middle of an array in csharp

remove an element from an array at a specific index in csharp

sort an array in csharp

add an element to the beginning of an array in csharp

related categories