Go to main content

man pages section 3: Basic Library Functions

Exit Print View

Updated: Wednesday, July 27, 2022



wcsxfrm, wcsxfrm_l, wsxfrm - wide character string transformation


#include <wchar.h> 

size_t wcsxfrm(wchar_t *ws1, const wchar_t *ws2, size_t n);
size_t wcsxfrm_l(wchar_t *ws1, const wchar_t *ws2, size_t n, locale_t locale);
size_t wsxfrm(wchar_t *ws1, const wchar_t *ws2, size_t n);


The wcsxfrm() and wcsxfrm() functions transform the wide character string pointed to by ws2 and place the resulting wide character string into the array pointed to by ws1. The transformation is such that if either the wcscmp(3C) or wscmp(3C) functions are applied to two transformed wide strings, they return a value greater than, equal to, or less than 0, corresponding to the result of the wcscoll(3C) or wscoll(3C) function applied to the same two original wide character strings. No more than n wide-character codes are placed into the resulting array pointed to by ws1, including the terminating null wide-character code. If n is 0, ws1 is permitted to be a null pointer. If copying takes place between objects that overlap, the behavior is undefined.

The fact that when n is 0, ws1 is permitted to be a null pointer, is useful to determine the size of the ws1 array prior to making the transformation.

The wcsxfrm() and wsxfrm() functions do not change the setting of errno if successful.

Since no return value is reserved to indicate an error, an application wishing to check for error situations should set errno to 0, then call wcsxfrm() or wsxfrm(), then check errno.

The wcsxfrm_l() function is equivalent to the wcsxfrm() function, except that the locale data used is from the locale represented by locale.

The behavior is undefined if the locale argument to wcsxfrm_l() is the special locale object LC_GLOBAL_LOCALE or is not a valid locale object handle.

Return Values

These functions return the length of the transformed wide character string (not including the terminating null wide-character code). If the value returned is n or more, the contents of the array pointed to by ws1 are indeterminate.

On error, these functions may set errno but no return value is reserved to indicate an error.


These functions may fail if:


The wide character string pointed to by ws2 contains wide-character codes outside the domain of the collating sequence.


See attributes(7) for descriptions of the following attributes:

Interface Stability
wcsxfrm() and wcsxfrm_l() are Standard

See Also

wscoll(3C), duplocale(3C), freelocale(3C), newlocale(3C), setlocale(3C), uselocale(3C), wcscmp(3C), wcscoll(3C), wscmp(3C), attributes(7), standards(7)