Convert camel case to snake case

camel2snake.php

<?php

/**
 * Convert camel case to snake case.
 * 
 * DISCLAIMER: Not mine. Got it from {@link http://stackoverflow.com/a/35719689}.
 * 
 * @param   string  $camelString  The source string.
 * @return  string                The converted string.
 */
function camel2snake($camelString)
{
    return strtolower(preg_replace(['/([a-z\d])([A-Z])/', '/([^_])([A-Z][a-z])/'], '$1_$2', $camelString));
}