The Open Group Base Specifications Issue 8
IEEE Std 1003.1-2024
Copyright © 2001-2024 The IEEE and The Open Group

NAME

towctrans, towctrans_l — wide-character transliteration

SYNOPSIS

#include <wctype.h>

wint_t towctrans(wint_t
wc, wctrans_t desc);

[CX] [Option Start] wint_t towctrans_l(wint_t wc, wctrans_t desc,
       locale_t
locale); [Option End]

DESCRIPTION

For towctrans(): [CX] [Option Start]  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. [Option End]

The towctrans() [CX] [Option Start]  and towctrans_l() [Option End]  functions shall transliterate the wide-character code wc using the mapping described by desc.

The current setting of the LC_CTYPE category in the current locale [CX] [Option Start]  or in the locale represented by locale, [Option End]  respectively, should be the same as during the call to wctrans() [CX] [Option Start]  or wctrans_l() [Option End]  that returned the value desc.

If the value of desc is invalid (that is, not obtained by a call to wctrans() or desc is invalidated by a subsequent call to setlocale() that has affected category LC_CTYPE ), the result is unspecified.

[CX] [Option Start] If the value of desc is invalid (that is, not obtained by a call to wctrans_l() with the same locale object locale) the result is unspecified. [Option End]

[CX] [Option Start] An application wishing to check for error situations should set errno to 0 before calling towctrans() or towctrans_l().

If errno is non-zero on return, an error has occurred.

The behavior is undefined if the locale argument to towctrans_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle. [Option End]

RETURN VALUE

If successful, the towctrans() [CX] [Option Start]  and towctrans_l() [Option End]  functions shall return the mapped value of wc using the mapping described by desc, or the value of wc unchanged if desc is zero. [CX] [Option Start]  Otherwise, they shall return wc unchanged. [Option End]

ERRORS

These functions may fail if:

[EINVAL]
[CX] [Option Start] desc contains an invalid transliteration descriptor. [Option End]

The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

The strings "tolower" and "toupper" are reserved for the standard mapping names. In the table below, the functions in the left column are equivalent to the functions in the right column.

towlower(wc)            towctrans(wc, wctrans("tolower"))
towlower_l(wc, locale)  towctrans_l(wc, wctrans("tolower"), locale)
towupper(wc)            towctrans(wc, wctrans("toupper"))
towupper_l(wc, locale)  towctrans_l(wc, wctrans("toupper"), locale)

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

towlower , towupper , wctrans

XBD <wctype.h>

CHANGE HISTORY

First released in Issue 5. Derived from ISO/IEC 9899:1990/Amendment 1:1995 (E).

Issue 6

Extensions beyond the ISO C standard are marked.

Issue 7

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

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0675 [302], XSH/TC1-2008/0676 [283], and XSH/TC1-2008/0677 [283] are applied.

Issue 8

Austin Group Defect 1302 is applied, aligning the towctrans() function with the ISO/IEC 9899:2018 standard.

End of informative text.

 

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