Search code examples
phpregexreplace

Replace text/string between two strings

I am struggling with regEx, but can not get it to work. I already try with: SO question, online tool,

$text = preg_replace("%/\*<##>(?:(?!\*/).)</##>*\*/%s", "new", $text);

But nothing works. My input string is:

$input = "something /*<##>old or something else</##>*/ something other";

and expected result is:

something /*<##>new</##>*/ something other
Solution

  • I see two issues that point out here, you have no capturing groups to replace the delimited markers inside your replacement call and your Negative Lookahead syntax is missing a repetition operator.

    $text = preg_replace('%(/\*<##>)(?:(?!\*/).)*(</##>*\*/)%s', '$1new$2', $text);

    Although, you can replace the lookahead with .*? since you are using the s (dotall) modifier.

    $text = preg_replace('%(/\*<##>).*?(</##>*\*/)%s', '$1new$2', $text);

    Or consider using a combination of lookarounds to do this without capturing groups.

    $text = preg_replace('%/\*<##>\K.*?(?=</##>\*/)%s', 'new', $text);