NAME

towlower, towlower_l — transliterate uppercase wide-character code to lowercase

SYNOPSIS

#include <wctype.h>

wint_t towlower(wint_t wc);


[CX] wint_t towlower_l(wint_t wc, locale_t locale);

DESCRIPTION

For towlower(): ^[CX]  The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1-2024 defers to the ISO C standard.

The towlower() ^[CX] and towlower_l()  functions have as a domain a type wint_t, the value of which the application shall ensure is a character representable as a wchar_t, and a wide-character code corresponding to a valid character in the locale used by the function or the value of WEOF. If the argument has any other value, the behavior is undefined. If the argument of towlower() ^[CX]  or towlower_l() represents an uppercase wide-character code, and there exists a corresponding lowercase wide-character code as defined by character type information in the current locale ^[CX]  or in the locale represented by locale,  respectively (category LC_CTYPE ), the result shall be the corresponding lowercase wide-character code. All other arguments in the domain are returned unchanged.

^[CX] The behavior is undefined if the locale argument to towlower_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.

RETURN VALUE

Upon successful completion, the towlower() ^[CX]  and towlower_l()  functions shall return the lowercase letter corresponding to the argument passed; otherwise, they shall return the argument unchanged.

ERRORS

No errors are defined.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

setlocale, uselocale

XBD 7. Locale, <locale.h>, <wctype.h>

CHANGE HISTORY

First released in Issue 4.

Issue 5

The following change has been made in this version for alignment with ISO/IEC 9899:1990/Amendment 1:1995 (E):

• The SYNOPSIS has been changed to indicate that this function and associated data types are now made visible by inclusion of the <wctype.h> header rather than <wchar.h>.

Issue 6

The normative text is updated to avoid use of the term "must" for application requirements.

Issue 7

The towlower_l() function is added from The Open Group Technical Standard, 2006, Extended API Set Part 4.

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0678 [302], XSH/TC1-2008/0679 [283], and XSH/TC1-2008/0680 [283] are applied.

POSIX.1-2008, Technical Corrigendum 2, XSH/TC2-2008/0373 [685] is applied.