How can I make Array.Contains case-insensitive on a string array?

Question

I am using the Array.Contains method on a string array. How can I make that case-insensitive?

Answer 1

Are you able to change the case of the strings before putting them into the array? For example, make them all lowercase to start with, and then use make string you pass to Contains lowercase too:

Array.Contains(s.ToLower()).

Answer 2

new[] { "ABC" }.Select(e => e.ToLower()).Contains("abc") // returns true

Answer 3

Implement a custom IEqualityComparer that takes case-insensitivity into account.

Additionally, check this out. So then (in theory) all you'd have to do is:

myArray.Contains("abc", ProjectionEqualityComparer<string>.Create(a => a.ToLower()))

Answer 4

array.Contains("str", StringComparer.InvariantCultureIgnoreCase);

Or depending on the specific circumstance, you might prefer:

array.Contains("str", StringComparer.OrdinalIgnoreCase);
array.Contains("str", StringComparer.CurrentCultureIgnoreCase);

Answer 5

Javascript function:

Array.prototype.contains = function (element) { for (var i = 0; i < this.length; i++) { if (this[i].toLowerCase() == element.toLowerCase()) { return true; } } return false; }