PHP 4.0 Bug #6740 Updated: * sometimes doesn't work like expected (doesn't match 0 characters)

ID: 6740 Updated by: andrei Reported By: thow@gmx.net Status: Closed Bug Type: PCRE related Assigned To: Comments: Fixed in CVS. Previous Comments: --------------------------------------------------------------------------- [2000-09-13 21:23:24] thow@gmx.net Update: this seems to be a problem with the backreferences, because when you have a string "abc##def#ghi" and you want to match everything between the hashmarks, the regexp "/#([^#]*?)#/" fails when there would be an empty backreference as it it would be at the 2 hashmarks after "abc" but "/(#[^#]*?#)/" works without any problem because there cannot be an empty backreference. Counclusion: empty backreferences don't work :-( --------------------------------------------------------------------------- [2000-09-13 18:54:13] thow@gmx.net SCRIPTS: ===== regexp.pl (works like expected): ====== #!/usr/bin/perl -w sub process_hashmark { my $s = shift @_; if ($s eq '') { print "Matched string: empty stringn"; } else { print "Matched string: $sn"; } return 'XX' if ($s eq ''); return 'ZZZ'; } my $s; my $regexp = 'X([^X]*?)X'; if (defined $ARGV[0]) { $s = $ARGV[0]; } else { $s = 'abcXdefXghi'; } print "Regular Expression: $regexpn"; print "String to process: $sn"; $s =~ s/$regexp/process_hashmark($1)/ge; print "Processed String: $sn"; ===== regexp.pl (end) regexp.php (works not like expected): ===== function process_hashmark($string) { if ($string == "") { print "Matched string: empty string<br>n"; } else { print "Matched string: $string<br>n"; } if ($string == "") return "XX"; return "ZZZ"; } $regexp = "X([^X]*?)X"; if (empty($s)) $s = "abcXdefXghi"; echo "Regular Expression: $regexp<br>n"; echo "String to process: $s<br>n"; $s = preg_replace("/$regexp/e", "process_hashmark(\1);", $s); echo "Processed string: $s<br>n"; ===== regexp.php (end) OUTPUT: ===== regexp.pl (case 1): Regular Expression: X([^X]*?)X String to process: abcXdefXghi Matched string: def Processed String: abcZZZghi regexp.pl (case 2): Regular Expression: X([^X]*?)X String to process: abcXXdefXghi Matched string: empty string Processed String: abcXXdefXghi regexp.php (case 1): Regular Expression: X([^X]*?)X String to process: abcXdefXghi Matched string: def Processed string: abcZZZghi regexp.php (case 2): Regular Expression: X([^X]*?)X String to process: abcXXdefXghi Matched string: XdefXghi Processed string: abcZZZdefXghi CONFIGURE LINE: ===== ./configure --with-apxs --with-pgsql=/usr/lib/pgsql --with-mysql=/usr php.ini should be irrelevant and there is nothing special in our setup --------------------------------------------------------------------------- Full Bug description available at: http://bugs.php.net/?id=6740