wctrans, wctrans_l - define character mapping
wctrans_t wctrans(const char *charclass);
[CX] wctrans_t wctrans_l(const char *charclass, locale_t locale);
For wctrans(): [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.1-2017 defers to the ISO C standard.
The wctrans() [CX] and wctrans_l() functions are defined for valid character mapping names identified in the current locale. The charclass is a string identifying a generic character mapping name for which codeset-specific information is required. The following character mapping names are defined in all locales: tolower and toupper.
These functions shall return a value of type wctrans_t, which can be used as the second argument to subsequent calls of towctrans() [CX] and towctrans_l().
The wctrans() [CX] and wctrans_l() functions shall determine values of wctrans_t according to the rules of the coded character set defined by character mapping information in the current locale [CX] or in the locale represented by locale, respectively (category LC_CTYPE).
The values returned by wctrans() shall be valid until a call to setlocale() that modifies the category LC_CTYPE.
[CX] The values returned by wctrans_l() shall be valid only in calls to towctrans_l() with a locale represented by locale with the same LC_CTYPE category value.
The behavior is undefined if the locale argument to wctrans_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.
The wctrans() [CX] and wctrans_l() functions shall return 0 and may set errno to indicate the error if the given character mapping name is not valid for the current locale (category LC_CTYPE); otherwise, they shall return a non-zero object of type wctrans_t that can be used in calls to towctrans() [CX] and towctrans_l().
These functions may fail if:
- [CX] The character mapping name pointed to by charclass is not valid in the current locale.
First released in Issue 5. Derived from ISO/IEC 9899:1990/Amendment 1:1995 (E).
The wctrans_l() function is added from The Open Group Technical Standard, 2006, Extended API Set Part 4.
POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0732 , XSH/TC1-2008/0733 , XSH/TC1-2008/0734 , and XSH/TC1-2008/0735  are applied.
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