C# Determine Duplicate in List [duplicate]

Answer 1

According to Eric White's article on how to Find Duplicates using LINQ:

An easy way to find duplicates is to write a query that groups by the identifier, and then filter for groups that have more than one member. In the following example, we want to know that 4 and 3 are duplicates:

int[] listOfItems = new[] { 4, 2, 3, 1, 6, 4, 3 };
var duplicates = listOfItems
    .GroupBy(i => i)
    .Where(g => g.Count() > 1)
    .Select(g => g.Key);
foreach (var d in duplicates)
    Console.WriteLine(d); // 4,3