将PHP正则表达式转换为c＃

Question

I have this regex:

<DIV(?:(?!</DIV>).)*?"(http://www\.foo\.com(?:\\.|[^"\\])*)"

And I am trying to use it using c#:

 @"<DIV(?:(?!</DIV>).)*?""(http://www\.foo\.com(?:\\.|[^""\\])*)"""

But this outputs every thing from <DIV onward I want it to just show inside the ""

Like the actual regex does

Answer 1

Since you are using capture groups (groups between a pair of parentheses ()), you will have to use Groups[#] to get the different parts of the capture group. Groups[1] will have the value of the first capture group.

If you are using:

@"<DIV(?:(?!</DIV>).)*?""(http://www\.foo\.com(?:\\.|[^""\\])*)"""

You will get the ones between " by using Groups[1].Value and the whole match in Groups[0].Value.

Example:

@"a(b(cd)(ef))"

Here you have 3 capture groups because there are 3 pairs of parentheses. After a match, and if you use:

Console.WriteLine(match.Groups[0].Value);
Console.WriteLine(match.Groups[1].Value);
Console.WriteLine(match.Groups[2].Value);
Console.WriteLine(match.Groups[3].Value);

You get:

abcdef
bcdef
cd
ef

If that's a little confusing, maybe this breakdown can help:

a(b(cd)(ef))
 1 2   3
   ^--|^--|
 ^---------|

The numbers and ^ indicate the beginning of the capture groups.