选择两个字符之间的所有内容而不包含它们

Question

I've been trying to look around for how to select everything between two characters in a string.

Example string:

@ Some text here @

To select this I did:

/@(.*)@/

But it includes the @ signs

I tried to use different methods I found online with no success.

Answer 1

It sounds like you are unfamiliar with the concept of capturing groups . From "Some text here", you can extract "ex" in the middle of the word "text" using something like /t(.+)t/ . While the entire match will be "text", group #1 will be just "ex".

You can use capturing groups in PHP by passing an empty variable/empty array as the third argument to preg_match($pattern, $subject, $matches) .

If $matches is provided, then it is filled with the results of search. $matches[0] will contain the text that matched the full pattern, $matches[1] will have the text that matched the first captured parenthesized subpattern, and so on.

Answer 2

What method are you working with? I'm gonna use preg_match_all to explain two possible regular expressions

$text = "hello @this is what i want@notthis!";

if (preg_match_all("/@([^@]*)@/", $text, $results))
    var_dump($results);
    // [0][0] "@this is what i want@"
    // [1][0] "this is what i want"

if (preg_match_all("/(?<=@)([^@]*)(?=@)/", $text, $results))
    var_dump($results);
    // [0][0] "this is what i want"
    // [1][0] "this is what i want"

If you have multiple occurences, you can loop through the first depth. So looping through $results[1] will always give you the correct string (since the brackets the string is in are the first in the searchable area).

As for the expressions:

1. The first one is the regular version. You look for a specified text (everything except @ ) inside specified characters. But since preg_match_all gives you the entire string it found plus the result, you get the @ as well.

2. The second expression uses so called lookaround. This means the characters insdie the first and last brackets are not part of the searched area but before/behind.