C# Determine Duplicate in List [duplicate]

Answer 1

You could use Distinct() statement to find unique records. Then compare with original generic list like this:

  if (dgCoil.ItemsSource.Cast().ToList().Count != dgCoil.ItemsSource.Cast().Select(c => c.CoilNo).Distinct().Count())
  {    
    //Duplicate detected !!
    return;
  }