为什么此C＃正则表达式不起作用？

Question

I have the following string (from a large HTML string):

href="/cgi-bin/pin.cgi?pin=94841&sid=9548.1386389012.v1"><

And here is my code:

var sids = Regex.Matches( htmlCode, "sid=(.)\">" );

I'm not pulling back any results. Is my Regex correct?

Answer 1

This is what it should be:

var str = @"href=""/cgi-bin/pin.cgi?pin=94841&sid=9548.1386389012.v1"">";
var sid = Regex.Match(str, @"sid=([^""]*)");
Console.WriteLine (sid.Groups[1].Value);

What you originally posted was wrong because "." acts as a wildcard, and the way you presented it meant that it would only capture 1 character, the problem with wildcards is that they're difficult to stop till you reach the end of a line, so never use them unless you have to.

Answer 2

. match only single character. To match multiple character you should use * or + modifier: (.+) ; or more preferably non-greedy version: (.+?)

Use @"verbatim string literal" if possible for regular expression.

var sids = Regex.Matches(htmlCode, @"sid=(.+?)""");

See demo run .

Answer 3

I think you are pretty close. Consider the following minor change to your regex...

sid=.*?\">

Good Luck!