How to convert camelCase to underscore in php?

Use PHP to convert the camelCase string into an underscore-separated or other character separated.

1. Code:

<?php 
	 function convertCamelCaseToUnderscore($str, $separator = "_"){
		$res = '';
		for ($i = 0; $i < strlen($str); $i++) {
			$ch = $str[$i];
			if (ctype_upper($ch)) {
				$res .= $separator.strtolower($ch);
			} else {
				$res .= $ch;
			}
		}
		return trim($res);
	}
	$str = "soltutsComIsProvidingPhpTutorials";
	 echo convertCamelCaseToUnderscore($str);
	 echo "<br>";
	 echo convertCamelCaseToUnderscore($str, " ");
    ?> 

2. Example:

Input:

soltutsComIsProvidingPhpTutorials

Output:

Soltuts_com_is_providing_php_tutorials