What is the correct way to compare char ignoring case?

Question

I\'m wondering what the correct way to compare two characters ignoring case that will work for all cultures. Also, is Comparer.Default the best way

Answer 1

You can provide last argument as true for caseInsensetive match

string.Compare(lowerCase, upperCase, true);

Answer 2

string.Compare("string a","STRING A",true)

It will work for every string

Answer 3

What I was thinking that would be available within the runtime is something like the following

public class CaseInsensitiveCharComparer : IComparer<char> {
    private readonly System.Globalization.CultureInfo ci;
    public CaseInsensitiveCharComparer(System.Globalization.CultureInfo ci) {
        this.ci = ci;
    }
    public CaseInsensitiveCharComparer()
        : this(System.Globalization.CultureInfo.CurrentCulture) { }
    public int Compare(char x, char y) {
        return Char.ToUpper(x, ci) - Char.ToUpper(y, ci);
    }
}

// Prints 3
Console.WriteLine("This is a test".CountChars('t', new CaseInsensitiveCharComparer()));