### 4.30 `towlower`, `towlower_l`—translate wide characters to lowercase ¶

Synopsis

    #include <wctype.h>
    wint_t towlower(wint_t c);

    #include <wctype.h>
    wint_t towlower_l(wint_t c, locale_t locale);

Description
`towlower` is a function which converts uppercase wide characters to lowercase, leaving all other characters unchanged.

`towlower_l` is like `towlower` but performs the function based on the locale specified by the locale object locale. If locale is LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.

Returns
`towlower`, `towlower_l` return the lowercase equivalent of c when it is a uppercase wide character; otherwise, it returns the input character.

Portability
`towlower` is C99. `towlower_l` is POSIX-1.2008.

No supporting OS subroutines are required.