down

Description:

public string down (ssize_t len = -1)

Converts all Unicode characters in the string that have a case to lowercase.

The exact manner that this is done depends on the current locale, and may result in the number of characters in the string changing.

len	length of `str`, in bytes, or -1 if `str` is nul-terminated.
str	a UTF-8 encoded string

a newly allocated string, with all characters converted to lowercase.