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

Here is my contribution to a six-year-old question with god knows how many answers...

It will convert all words in the provided string that are in camelcase to snakecase. For example "SuperSpecialAwesome and also FizBuzz καιΚάτιΑκόμα" will be converted to "super_special_awesome and also fizz_buzz και_κάτι_ακόμα".

mb_strtolower(
    preg_replace_callback(
        '/(?