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<?php echo preg_replace("/(?!^)(?=[A-Z])/", "_", "FooBarAoo"); echo strtolower(preg_replace('/([A-Z])/', '_$1', lcfirst("FooBarAoo")));
Output for 5.3.0 - 5.6.28, hhvm-3.10.0 - 3.12.0, 7.0.0 - 7.1.0
Foo_Bar_Aoofoo_bar_aoo
Output for 5.2.3 - 5.2.17
Foo_Bar_Aoo Fatal error: Call to undefined function lcfirst() in /in/EHJKv on line 4
Process exited with code 255.
Output for 5.0.0 - 5.2.2
Foo_Bar_Aoo<br /> <b>Fatal error</b>: Call to undefined function lcfirst() in <b>/in/EHJKv</b> on line <b>4</b><br />
Process exited with code 255.
Output for 4.4.5 - 4.4.9
Foo_Bar_Aoo<br /> <b>Fatal error</b>: Call to undefined function: lcfirst() in <b>/in/EHJKv</b> on line <b>4</b><br />
Process exited with code 255.
Output for 4.3.2 - 4.4.4
Foo_Bar_Aoo<br /> <b>Fatal error</b>: Call to undefined function: lcfirst() in <b>/in/EHJKv</b> on line <b>4</b><br />
Process exited with code 255.
Output for 4.3.0 - 4.3.1
Foo_Bar_Aoo<br /> <b>Fatal error</b>: Call to undefined function: lcfirst() in <b>/in/EHJKv</b> on line <b>4</b><br />