check a list for duplicates c# code example

Example 1: c# find duplicates in list

var query = lst.GroupBy(x => x)
              .Where(g => g.Count() > 1)
              .Select(y => y.Key)
              .ToList();

Example 2: c# see if list contains any duplicates

var list = new List<string>();

// Fill the list

if(list.Count != list.Distinct().Count())
{
     // Duplicates exist
}