---
name: "wctrans"
section: "3p"
platform: "linux"
package: "man-pages"
version: "6.19-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/wctrans/3p"
---

# wctrans(3p)

define character mapping

## PROLOG

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

## NAME

wctrans, wctrans\_l — define character mapping

## SYNOPSIS

```
#include <wctype.h>
```

wctrans\_t wctrans(const char \**charclass*); wctrans\_t wctrans\_l(const char \**charclass*, locale\_t *locale*);

## DESCRIPTION

For *wctrans*(): 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*() 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*() and *towctrans\_l*().

The *wctrans*() 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 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*.

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.

## RETURN VALUE

The *wctrans*() 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*() and *towctrans\_l*().

## ERRORS

These functions may fail if:

- **EINVAL**

  The character mapping name pointed to by *charclass* is not valid in the current locale.

*The following sections are informative.*

## EXAMPLES

None.

## APPLICATION USAGE

None.

## RATIONALE

None.

## FUTURE DIRECTIONS

None.

## SEE ALSO

*towctrans()*

The Base Definitions volume of POSIX.1‐2017, ***\<wctype.h\>***

## COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting\_bugs.html .