towlower man page

towlower, towlower_l — convert a wide character to lowercase


#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:


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.

Return Value

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


The towlower_l() function first appeared in glibc 2.3.


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

Conforming to

towlower(): C99, POSIX.1-2001 (XSI); present as an XSI extension in POSIX.1-2008, but marked obsolete.

towlower_l(): 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.

See Also

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


This page is part of release 4.11 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at

Referenced By

iswlower(3), toupper(3), towctrans(3), towupper(3), wcscasecmp(3), wcsncasecmp(3).

towlower_l(3) is an alias of towlower(3).

2016-10-08 GNU Linux Programmer's Manual