Doc #73913 [Asn->Csd]: broken strrpos with negative offset

Edit report at https://bugs.php.net/bug.php?id=73913&edit=1 ID: 73913 Updated by: girgias@php.net Reported by: proartex at mail dot ru Summary: broken strrpos with negative offset -Status: Assigned +Status: Closed Type: Documentation Problem Package: Strings related Operating System: macOS Sierra 10.12.1 PHP Version: 5.6.29 Assigned To: girgias Block user comment: N Private report: N Previous Comments: ------------------------------------------------------------------------ [2019-04-23 00:51:33] girgias@php.net Automatic comment from SVN on behalf of girgias Revision: http://svn.php.net/viewvc/?view=revision&revision=347318 Log: Fix Doc Bug #73913 A better description of how the offset parameter works (especially with negative offsets) Added some examples to illustrate how offset affects the function. Maybe an example that compares this to strpos should be there too? ------ Inspired by anonymous 96388 (php.florianberberich@outlook.com) ------------------------------------------------------------------------ [2018-10-01 18:18:58] cmb@php.net > Java implementation has no negative fromIndex for "public int > lastIndexOf(String str, int fromIndex)". If the offset is negative, strrpos($haystack, $needle, $offset) behaves like String.lastIndexOf(needle, -offset). > It works the way we expect Then you have to adjust your expectations. :) Or, your code. For instance: strrpos('works_like_a_charm', 'charm', -3 - strlen('charm')); // false ------------------------------------------------------------------------ [2017-01-13 16:28:01] dima at virtuman dot com Java implementation has no negative fromIndex for "public int lastIndexOf(String str, int fromIndex)". Java implementation returns "-1" for any negative fromIndex. There is an examples from python: " >>> 'aaaa'.rfind('a',0, -2) 1 >>> 'aaaa'.rfind('a', 0, -1) 2 >>> '/documents/show/5474'.rfind('/', 0, -20) -1 >>> 'works_like_a_charm'.rfind('charm', 0, -3) -1 >>> 'works_like_a_charm'.rfind('charm', 0, -5) -1 " It works the way we expect ------------------------------------------------------------------------ [2017-01-13 15:48:10] heiglandreas@php.net For more infos have a look at https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#lastIndexOf(java.lang.String,%20int) ------------------------------------------------------------------------ [2017-01-13 15:46:33] heiglandreas@php.net The current implementation is mathematically correct and is the same as f.e. the implementation in Java and other programming languages. The docs are misleading here. The negative offset specifies the last offset in the string the needle can start. Therefore the results are correct. Though the documentation of that feature needs some work to explicitly state that and make that more clear. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=73913 -- Edit this bug report at https://bugs.php.net/bug.php?id=73913&edit=1