Question

This is supposedly a very easy question, but I just can’t seem to find the right solution. There is a string in the format:

A:B=C;D:E=F;G:E=H;...

whereas A, B and C are alphanumeric (and may be lower as well as upper case). A and B are of length 1+, C may be empty.

I figured I’d have to use something along the lines of

((?<A>.+):(?<B>.+)=(?<C>.*);)*

but I don’t see how to make it match in a lazy way. I’m also not sure how to obtain the results of the respective matches so I’d appreciate a little code sample.

I’d be glad if you could give me a hint.

Answer 1

You might use \w to match alphanumeric characters rather than ., which matches everything. Then, you might try to capture one match at a time:

(?<A>\w+):(?<B>\w+)=(?<C>\w*);

Here’s a small example:

Regex regex = new Regex("(?<A>\\w+):(?<B>\\w+)=(?<C>\\w*);");
string test = "A:B=C;D:E=F;G:E=H";

// get all matches
MatchCollection mc = regex.Matches(test);

foreach (Match m in mc) { 
    Console.WriteLine("A = {0}", m.Groups["A"].Value);
    Console.WriteLine("B = {0}", m.Groups["B"].Value);
    Console.WriteLine("C = {0}", m.Groups["C"].Value);
}

note: there are several tools that allow you to experiment with regular expressions and also provide some sort of help; I personally like Expresso – try it out, it will be very useful for learning.