towupper(3) Library Functions Manual towupper(3)

towupper, towupper_l - convert a wide character to uppercase

Standard C library (libc, -lc)

#include <wctype.h>
wint_t towupper(wint_t wc);
wint_t towupper_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 towupper() function is the wide-character equivalent of the toupper(3) function. If wc is a lowercase wide character, and there exists an uppercase equivalent in the current locale, it returns the uppercase equivalent of wc. In all other cases, wc is returned unchanged.

The towupper_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 towupper_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 uppercase, towupper() returns its uppercase equivalent; otherwise it returns wc.

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

Interface Attribute Value
towupper () Thread safety MT-Safe locale
towupper_l () Thread safety MT-Safe

C11, POSIX.1-2008 (XSI).

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

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.

iswupper(3), towctrans(3), towlower(3), locale(7)

2024-05-02 Linux man-pages 6.8