The Open Group Base Specifications Issue 7
IEEE Std 1003.1, 2013 Edition
Copyright © 2001-2013 The IEEE and The Open Group

#### 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.1-2008 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 current locale 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.

The following sections are informative.

#### EXAMPLES

> None.

#### APPLICATION USAGE

> None.

#### RATIONALE

> None.

#### FUTURE DIRECTIONS

> None.

#### SEE ALSO

> setlocale, uselocale

> XBD 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.

End of informative text.

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