How to convert PascalCase to pascal_case?

Question

If I had:

$string = \"PascalCase\";

I need

\"pascal_case\"

Does PHP offer a function for this purpose?

Answer 1

I had a similar problem but couldn't find any answer that satisfies how to convert CamelCase to snake_case, while avoiding duplicate or redundant underscores _ for names with underscores, or all caps abbreviations.

Th problem is as follows:

CamelCaseClass            => camel_case_class
ClassName_WithUnderscores => class_name_with_underscore
FAQ                       => faq

The solution I wrote is a simple two functions call, lowercase and search and replace for consecutive lowercase-uppercase letters:

strtolower(preg_replace("/([a-z])([A-Z])/", "$1_$2", $name));