Doc #80166 [Com]: preg_match_all()'s PREG_OFFSET_CAPTURE ignoring modifier u

Edit report at https://bugs.php.net/bug.php?id=80166&edit=1 ID: 80166 Comment by: thomas at landauer dot at Reported by: thomas at landauer dot at Summary: preg_match_all()'s PREG_OFFSET_CAPTURE ignoring modifier u Status: Closed Type: Documentation Problem Package: PCRE related Operating System: Linux PHP Version: 7.2.33 Assigned To: cmb Block user comment: N Private report: N New Comment: > The use of character offsets should be avoided wherever possible. Why? When using *byte* offsets to split a string, you might end up with an invalid string, due to some "half"-characters. Previous Comments: ------------------------------------------------------------------------ [2020-10-01 12:20:12] phpdocbot@php.net Automatic comment on behalf of cmb Revision: http://git.php.net/?p=doc/en.git;a=commit;h=7d4c08228e566afb3caedd29cb837a2fa67fcfbf Log: Fix #80166: preg_match_all()'s PREG_OFFSET_CAPTURE ignoring modifier u ------------------------------------------------------------------------ [2020-10-01 12:16:41] nikic@php.net Right, the clarification here should be that this is always a "byte offset" including in UTF8 mode. ------------------------------------------------------------------------ [2020-10-01 12:14:30] cmb@php.net > PREG_OFFSET_CAPTURE always counts utf-8 special characters as > *2* (bytes) To clarify: UTF-8 characters are not necessarily counter as 2 bytes. ------------------------------------------------------------------------ [2020-10-01 12:10:26] nikic@php.net The documentation should be clarified, but the current behavior is both intentional and preferable. The use of character offsets should be avoided wherever possible. ------------------------------------------------------------------------ [2020-10-01 12:02:18] thomas at landauer dot at Description: ------------ PREG_OFFSET_CAPTURE always counts utf-8 special characters as *2* (bytes) - no matter if the modifier u (PCRE_UTF8) is present or not. This has been reported before at https://bugs.php.net/bug.php?id=37391 but got closed as "Not a bug". However, taking a look at the documentation clearly shows that this *is* a bug: https://www.php.net/manual/en/function.preg-match-all.php#refsect1-function.preg-match-all-parameters says about PREG_OFFSET_CAPTURE > If this flag is passed, for every occurring match the appendant string offset will also be > returned. "string offset" obviously refers to the number of *characters* in front of the match. And https://www.php.net/manual/en/reference.pcre.pattern.modifiers.php says about u (PCRE_UTF8): > Pattern and subject strings are treated as UTF-8. My actual PHP version is 7.2.24 Test script: --------------- preg_match_all('/a/u', 'öa', $matches, PREG_OFFSET_CAPTURE); var_dump($matches); Expected result: ---------------- [1]=>int(1) Actual result: -------------- [1]=>int(2) (=expected result without modifier u) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=80166&edit=1