ID: 29427
Comment by: skissane at iips dot mq dot edu dot au
Reported By: x-g at monkeyblah dot com
Status: Open
Bug Type: *Regular Expressions
Operating System: Windows XP
PHP Version: 4.3.8
New Comment:
The behaviour the manual implies is far more useful for my application.
This is because I need to repeatedly match the beginning of substrings,
but using substr(...) results in excessive memory usage, especially
when the strings are very large.
I would encourage this bug to be fixed ASAP.
Previous Comments:
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[2004-07-28 13:29:41] x-g at monkeyblah dot com
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
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Edit this bug report at http://bugs.php.net/?id=29427&edit=1
