towlower(3) Library Functions Manual towlower(3)

towlower, towlower_l - convert a wide character to lowercase

Standard C library (libc, -lc)

#include <wctype.h>
wint_t towlower(wint_t wc);
wint_t towlower_l(wint_t wc, locale_t locale);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):


    Since glibc 2.10:
        _XOPEN_SOURCE >= 700
    Before glibc 2.10:

The towlower() function is the wide-character equivalent of the tolower(3) function. If wc is an uppercase wide character, and there exists a lowercase equivalent in the current locale, it returns the lowercase equivalent of wc. In all other cases, wc is returned unchanged.

The towlower_l() function performs the same task, but performs the conversion based on the character type information in the locale specified by locale. The behavior of towlower_l() is undefined if locale is the special locale object LC_GLOBAL_LOCALE (see duplocale(3)) or is not a valid locale object handle.

The argument wc must be representable as a wchar_t and be a valid character in the locale or be the value WEOF.

If wc was convertible to lowercase, towlower() returns its lowercase equivalent; otherwise it returns wc.

For an explanation of the terms used in this section, see attributes(7).

Interface Attribute Value
towlower () Thread safety MT-Safe locale
towlower_l () Thread safety MT-Safe

C11, POSIX.1-2008 (XSI).

C99, POSIX.1-2001 (XSI). Obsolete in POSIX.1-2008 (XSI).
glibc 2.3. POSIX.1-2008.

The behavior of these functions depends on the LC_CTYPE category of the locale.

These functions are not very appropriate for dealing with Unicode characters, because Unicode knows about three cases: upper, lower, and title case.

iswlower(3), towctrans(3), towupper(3), locale(7)

2024-05-02 Linux man-pages 6.8