正则表达式提取子串

Question

really struggling with this...hopefully someone can put me on the right path to a solution.

My input string is structured like this:

66-2141-A-AC107-7

I'm interested in extracting the string 'AC107' using a single regular expression. I know how to do this with other PHP string functions, but I have to do this with a regular expression.

What I need is to extract all data between the third and fourth hyphens. The structure of each section is not fixed (i.e, 66 may be 8798709 and 2141 may be 38). The presence of the number of hyphens is guaranteed (i.e., there will always be a total of four (4) hyphens).

Any help/guidance is greatly appreciated!

Answer 1

This will do what you need:

(?:[^-]*-){3}([^-]+)

Debuggex Demo

Explanation:

• (?:[^-]*-) Look for zero or more non-hyphen characters followed by a hyphen
• {3} Look for three of the blocks just described
• ([^-]+) Capture all the consecutive non-hyphen characters from that point forward (will automatically cut off before the next hyphen)

You can use it in PHP like this:

$str = '66-2141-A-AC107-7';
preg_match('/^(?:[^-]*-){3}([^-]+)/', $str, $matches);
echo $matches[1];  // prints AC107