Question

Given the following simple example:

    List<string> list = new List<string>() { 'One', 'Two', 'Three', 'three', 'Four', 'Five' };      CaseInsensitiveComparer ignoreCaseComparer = new CaseInsensitiveComparer();      var distinctList = list.Distinct(ignoreCaseComparer as IEqualityComparer<string>).ToList(); 

It appears the CaseInsensitiveComparer is not actually being used to do a case-insensitive comparison.

In other words distinctList contains the same number of items as list. Instead I would expect, for example, ‘Three’ and ‘three’ be considered equal.

Am I missing something or is this an issue with the Distinct operator?

Answer 1

StringComparer does what you need:

List<string> list = new List<string>() {     'One', 'Two', 'Three', 'three', 'Four', 'Five' };  var distinctList = list.Distinct(     StringComparer.CurrentCultureIgnoreCase).ToList(); 

(or invariant / ordinal / etc depending on the data you are comparing)