ID: 50434
Comment by: mail at daniel-faber dot de
Reported By: mail at daniel-faber dot de
Status: Analyzed
Bug Type: Feature/Change Request
PHP Version: 5.2.11
New Comment:
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)) == $p because it's shorter and easier to
read.
This functionality is so often needed and when you need it, you have do
use the substr expression or define you own str_startswith function. So
why not adding it to the PHP core since it's such a basic thing...
Previous Comments:
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[2009-12-10 00:58:48] mail at daniel-faber dot de
rasmus, this is right in nearly all cases, but here are some corner
cases where your code fails:
startswith('', '0')
should be false, but your code gives true
reason: substr('', 0, 1) is false
false == '0' is true
if you try to fix this by replacing == with ===, another corner case
will fail:
startswith('', '')
should be true, but will be false
reason: substr('', 0, 0) is false
false === '' is false
this seems to work in all cases:
function str_startswith($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) == $suffix;
}
------------------------------------------------------------------------
[2009-12-09 23:48:49] [email protected]
Isn't it super trivial given the way substr works in PHP?
startswith:
substr($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)
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Edit this bug report at http://bugs.php.net/?id=50434&edit=1
