Get Second to last character position from string

Question

I have a dynamically formed string like - part1.abc.part2.abc.part3.abc

In this string I want to know position of second to last \".\" so that i can split string as

Answer 1

string str = "part1.abc.part2.abc.part3.abc";
int ix1 = str.LastIndexOf('.');
int ix2 = ix1 > 0 ? str.LastIndexOf('.', ix1 - 1) : -1;

There are always lovers of Regexes (and jQuery), so I'll give a Regex solution (for the jQuery solution you'll have to wait :-) ):

var match = Regex.Match(str, @"\.[^\.]*\.", RegexOptions.RightToLeft);
int ix = match.Success ? match.Index : -1;

(note that I'm an hater of Regexes, I'm giving it to you so that you can have enough rope to hang yourself if you so choose).

Be aware that I'm using the RegexOptions.RightToLeft option so that the Regex starts at the last character.