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<?php //echo preg_replace('/(?:(?!dog).)++/', '<$0>', 'where my dog is now?'); echo preg_replace('/(?!ba)..|..(*SKIP)/', '<$0>', 'aabaabaaaaabbb');
Output for 4.4.9, 5.2.5 - 5.6.28, hhvm-3.10.0 - 3.12.0, 7.0.0 - 7.1.0
<aa><ba><ab><aa><aa><ab><bb>
Output for 4.3.11 - 4.4.8, 5.0.0 - 5.2.4
Warning: preg_replace(): Compilation failed: nothing to repeat at offset 12 in /in/5I8o1 on line 3
Output for 4.3.0 - 4.3.10
Warning: Compilation failed: nothing to repeat at offset 12 in /in/5I8o1 on line 3