Bug #12668 Updated: unexpected behavior of preg_replace

ID: 12668 User updated by: chuck@1111-internet.com Reported By: chuck@1111-internet.com Status: Analyzed Bug Type: PCRE related Operating System: FreeBSD 4.0 PHP Version: 4.0.6 New Comment: Ah - I see - so what I'm seeing is actually a symptom of the basic issue that addslashes() is not a perfect reciprocal to putting addslashes-affected characters inside a string - i.e.: <?php // double-quoted strings echo "\""; // produces " echo "\\"; // produces \ // but echo "\'"; // produces \' // single-quoted strings echo '\''; // produces ' echo '\\'; // produces \ // but echo '\"'; // produces \" ?> whereas in mysql: select "\""; # produces " select "\\"; # produces \ select "\'"; # produces ' and perl is yet again different (with strings in single-quotes anyway): print "\""; # produces " print "\\"; # produces \ print "\'"; # produces ' print '\''; # produces ' print '\\'; # produces \\ print '\"'; # produces " I suppose backward compatibility would prevent this core behavior from being changed at this stage - it's just kinda screwy that both single-quoting and double-quoting of strings is a bit of a compromise in terms of slashed characters. Perhaps instead of sending preg_replace carry-forward values through the entire addslashes routine, only " and \ could be returned as slashed, and users could stick with using double-quotes for strings within the (eval'd) replace string... that would prevent people from having to use a hack get it to work as expected. Thanks, Chuck Previous Comments: ------------------------------------------------------------------------ [2001-08-09 09:19:18] alindeman@php.net of course I meant addslashes() ------------------------------------------------------------------------ [2001-08-09 09:18:47] alindeman@php.net how about creating either two different functions, or another attribute to preg_replace, that you can set true/false to run that add_slashes or not? ------------------------------------------------------------------------ [2001-08-09 09:03:31] andrei@php.net This is because preg_replace() runs addslashes() internally on the captured subpatterns before substrituting them into the replacement string. It didn't used to but a few people complained that it was really hard to pass $n to a function because of single and double-quote conflicts. To be frank, I'm not sure how to solve this problem adequately, one group of people want the addslashes() run, the other one doesn't. ------------------------------------------------------------------------ [2001-08-08 21:06:50] chuck@1111-internet.com Simple problem - the script: <?php echo preg_replace("/'/e", "\"$0\"", "'"); // that's double-quote, slash, single-quote, slash, e, double-quote // then double-quote, escaped double-quote, $0, escaped double-quote, double-quote // then double-quote, single-quote, double-quote // meaning = "replace all occurrences of single-quote with the same string matched during the search - i.e. single-quote" ?> should produce one plain single-quote, but instead it produces an escaped single-quote. No other character seems to exhibit this behavior. Configuration: './configure' '--prefix=/usr/local/php4' '--with-mysql' '--with-apxs=/usr/local/sbin/apxs' '--enable-track-vars' '--with-gd=/usr/local' '--with-zlib-dir=shared' '--with-ttf' '--with-jpeg-dir=/usr/local' '--with-png-dir=/usr/local' '--with-tiff-dir=/usr/local' '--with-mcrypt' '--with-pdflib' No other unusual configuration setups ------------------------------------------------------------------------ Edit this bug report at http://bugs.php.net/?id=12668&edit=1