Req #50434 [Com]: add string functions str_startswith and str_endswith for convenience

Edit report at https://bugs.php.net/bug.php?id=50434&edit=1 ID: 50434 Comment by: ajf at ajf dot me Reported by: mail at daniel-faber dot de Summary: add string functions str_startswith and str_endswith for convenience Status: Analyzed Type: Feature/Change Request Package: Strings related PHP Version: 5.2.11 Block user comment: N Private report: N New Comment: I would also like to see this. It's very handy for string checking. Both Python and C# have such a method. (accompanied by Python's in, it's very handy) For brevity I'd prefer startswith() and endswith(), however. I think I'll write a patch :) Previous Comments: ------------------------------------------------------------------------ [2009-12-10 13:19:38] mail at daniel-faber dot de Possible problems with the above corner cases are not the main reasons why I requested these functions. Even if I know this corner cases will not occur in my application I'll prefer str_startswith($s, $p) to substr($s, 0, strlen($p)) == $p because it's shorter and easier to read. This functionality is so often needed and when you need it, you have do use the substr expression or define you own str_startswith function. So why not adding it to the PHP core since it's such a basic thing... ------------------------------------------------------------------------ [2009-12-10 00:58:48] mail at daniel-faber dot de rasmus, this is right in nearly all cases, but here are some corner cases where your code fails: startswith('', '0') should be false, but your code gives true reason: substr('', 0, 1) is false false == '0' is true if you try to fix this by replacing == with ===, another corner case will fail: startswith('', '') should be true, but will be false reason: substr('', 0, 0) is false false === '' is false this seems to work in all cases: function str_startswith($string, $prefix) { if (strlen($string) < strlen($prefix)) return false; return substr($string, 0, strlen($prefix)) == $prefix; } similar for endswith: endswith('', '0') should be false, but is true endswith('test', '') should be true, but is false this seems to work in all cases: function str_endswith($string, $suffix) { $suffixLength = strlen($suffix); if ($suffixLength == 0) return true; if (strlen($string) < $suffixLength) return false; return substr($string, -$suffixLength) == $suffix; } ------------------------------------------------------------------------ [2009-12-09 23:48:49] rasmus@php.net Isn't it super trivial given the way substr works in PHP? startswith: substr($haystack,0,strlen($prefix)) == $prefix endswith: substr($haystack,-strlen($suffix)) == $suffix Usually we add things to core that can't be done with a single trivial call in PHP. The only thing you save is the strlen call, and you can hardcode that to avoid it. ------------------------------------------------------------------------ [2009-12-09 23:39:58] mail at daniel-faber dot de Description: ------------ Please add these two string functions for convenience: boolean str_startswith($string, $prefix) // true if $string starts with $prefix, false otherwise boolean str_endswith($string, $suffix) // true if $string ends with $suffix, false otherwise Of course one can easily write these functions in PHP, but having them in the PHP core would be nice. You find them in other languages too: Java: string.startsWith(prefix) and string.endsWith(suffix) Python: string.startswith(prefix) and string.endswith(suffix) ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=50434&edit=1