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<?php echo preg_replace_callback("#_([a-z])#",function($r){ return ucfirst($r); },'abc_def_ghj');
Output for 8.2.0 - 8.2.18, 8.3.0 - 8.3.7
Fatal error: Uncaught TypeError: ucfirst(): Argument #1 ($string) must be of type string, array given in /in/M2oDJ:4 Stack trace: #0 /in/M2oDJ(4): ucfirst(Array) #1 [internal function]: {closure}(Array) #2 /in/M2oDJ(3): preg_replace_callback('#_([a-z])#', Object(Closure), 'abc_def_ghj') #3 {main} thrown in /in/M2oDJ on line 4
Process exited with code 255.
Output for 8.0.0 - 8.0.30, 8.1.0 - 8.1.28
Fatal error: Uncaught TypeError: ucfirst(): Argument #1 ($string) must be of type string, array given in /in/M2oDJ:4 Stack trace: #0 /in/M2oDJ(4): ucfirst(Array) #1 [internal function]: {closure}(Array) #2 /in/M2oDJ(5): preg_replace_callback('#_([a-z])#', Object(Closure), 'abc_def_ghj') #3 {main} thrown in /in/M2oDJ on line 4
Process exited with code 255.
Output for 5.3.0 - 5.3.29, 5.4.0 - 5.4.45, 5.5.0 - 5.5.38, 5.6.0 - 5.6.40, 7.0.0 - 7.0.33, 7.1.0 - 7.1.33, 7.2.0 - 7.2.33, 7.3.0 - 7.3.33, 7.4.0 - 7.4.33
Warning: ucfirst() expects parameter 1 to be string, array given in /in/M2oDJ on line 4 Warning: ucfirst() expects parameter 1 to be string, array given in /in/M2oDJ on line 4 abcefhj
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_FUNCTION in /in/M2oDJ 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_FUNCTION in /in/M2oDJ on line 3
Process exited with code 255.
Output for 4.3.2 - 4.3.4
Parse error: parse error in /in/M2oDJ on line 3
Process exited with code 255.

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