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:

";
	 echo convertCamelCaseToUnderscore($str, " ");
    ?> 

2. Example:

Input:

soltutsComIsProvidingPhpTutorials

Output:

Soltuts_com_is_providing_php_tutorials