From: x-g at monkeyblah dot com
Operating system: Windows XP
PHP version: 4.3.8
PHP Bug Type: *Regular Expressions
Bug description: preg_match offset not equivalent to substr
Description:
------------
According to the manual, passing an offset to preg_match is equivalent to
passing substr($string, $offset) to the function. This is not the case,
however; regular expressions that match on beginning-of-string will not
match if an offset is specified, but work fine if substr() is used in a
supposedly equivalent manner.
Either this is a problem with regular expressions giving unexpected
behaviour, or perhaps the manual just need to be changed to reflect the
difference.
Reproduce code:
---------------
$string = "abc def";
if (preg_match("/^[a-zA-Z]+/", $string, $matches, 0, 4))
echo "Matches\n";
else
echo "Does not match\n";
if (preg_match("/^[a-zA-Z]+/", substr($string, 4), $matches, 0))
echo "Matches\n";
else
echo "Does not match\n";
Expected result:
----------------
Matches
Matches
Actual result:
--------------
Does not match
Matches
--
Edit bug report at http://bugs.php.net/?id=29427&edit=1
--
Try a CVS snapshot (php4): http://bugs.php.net/fix.php?id=29427&r=trysnapshot4
Try a CVS snapshot (php5): http://bugs.php.net/fix.php?id=29427&r=trysnapshot5
Fixed in CVS: http://bugs.php.net/fix.php?id=29427&r=fixedcvs
Fixed in release: http://bugs.php.net/fix.php?id=29427&r=alreadyfixed
Need backtrace: http://bugs.php.net/fix.php?id=29427&r=needtrace
Need Reproduce Script: http://bugs.php.net/fix.php?id=29427&r=needscript
Try newer version: http://bugs.php.net/fix.php?id=29427&r=oldversion
Not developer issue: http://bugs.php.net/fix.php?id=29427&r=support
Expected behavior: http://bugs.php.net/fix.php?id=29427&r=notwrong
Not enough info: http://bugs.php.net/fix.php?id=29427&r=notenoughinfo
Submitted twice: http://bugs.php.net/fix.php?id=29427&r=submittedtwice
register_globals: http://bugs.php.net/fix.php?id=29427&r=globals
PHP 3 support discontinued: http://bugs.php.net/fix.php?id=29427&r=php3
Daylight Savings: http://bugs.php.net/fix.php?id=29427&r=dst
IIS Stability: http://bugs.php.net/fix.php?id=29427&r=isapi
Install GNU Sed: http://bugs.php.net/fix.php?id=29427&r=gnused
Floating point limitations: http://bugs.php.net/fix.php?id=29427&r=float
