System.String.IndexOf (char)

string.IndexOf(char)ってculture insensitiveなんだよねー。

CompareInfo ci = CultureInfo.InvariantCulture.CompareInfo;  

Console.WriteLine ("AE".IndexOf ('\u00C6'));  

Console.WriteLine ("AE".IndexOf ("\u00C6"));  

Console.WriteLine (ci.IndexOf ("AE", '\u00C6'));

 -1  

 0  

 0