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<?php $regex = <<<'REGEX' ~ <strong\s*> # Match strong open tag ( # Open group 1 (?: # Non-capturing group (?:(?!</?strong\s*>).) # Match anything that's not strong tag (open/close) | # Or (?R) # Repeat the whole pattern )* # Repeat the non-capturing group zero or more times ) # Close group 1 </strong\s*> # Match strong close tag ~xs REGEX; # The x modifier is for the fancy spacing en commenting # The s modifier is to match newlines with dot "." $output = preg_replace_callback($regex, function($m){ return '<strong>' . preg_replace('~</?strong\s*>~', '', $m[1]) . '</strong>'; }, $input); echo $output; // w1 <strong>w2</strong> w3 w4 <strong>w5 w6</strong> w7
Output for 8.2.0 - 8.2.18, 8.3.0 - 8.3.6
Warning: Undefined variable $input in /in/D6MPi on line 21 Deprecated: preg_replace_callback(): Passing null to parameter #3 ($subject) of type array|string is deprecated in /in/D6MPi on line 19
Output for 8.1.0 - 8.1.28
Warning: Undefined variable $input in /in/D6MPi on line 21 Deprecated: preg_replace_callback(): Passing null to parameter #3 ($subject) of type array|string is deprecated in /in/D6MPi on line 21
Output for 8.0.0 - 8.0.30
Warning: Undefined variable $input in /in/D6MPi on line 21
Output for 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.24 - 5.5.35, 5.6.7 - 5.6.28, 7.0.0 - 7.0.20, 7.1.0 - 7.1.10, 7.2.0 - 7.2.33, 7.3.12 - 7.3.31, 7.4.0 - 7.4.33
Notice: Undefined variable: input in /in/D6MPi on line 21
Output for 7.3.32 - 7.3.33
Output for 4.4.2 - 4.4.9, 5.1.0 - 5.1.6, 5.2.0 - 5.2.17
Parse error: syntax error, unexpected T_SL in /in/D6MPi on line 3
Process exited with code 255.
Output for 4.3.0 - 4.3.1, 4.3.5 - 4.3.11, 4.4.0 - 4.4.1, 5.0.0 - 5.0.5
Parse error: parse error, unexpected T_SL in /in/D6MPi on line 3
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error in /in/D6MPi on line 3
Process exited with code 255.
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251.57 ms | 401 KiB | 314 Q