#include <wchar.h>size_t wcsxfrm(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 wcsxfrm() and wsxfrm() 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, wcsxfrm() and wsxfrm() return (size_t)-1 and set errno to indicate the error.
The wcsxfrm() and wsxfrm() functions may fail if:
The wide character string pointed to by ws2 contains wide-character codes outside the domain of the collating sequence.
The function is not supported.
The transformation function is such that two transformed wide character strings can be ordered by the wcscmp() or wscmp() functions as appropriate to collating sequence information in the program's locale (category LC_COLLATE).
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.
Because no return value is reserved to indicate an error, an application wishing to check for error situations should set errno to 0, call wcsxfrm() or wsxfrm(), then check errno and if it is non-zero, assume an error has occurred.
The wcsxfrm() and wsxfrm() functions can be used safely in multithreaded applications as long as setlocale(3C) is not being called to change the locale.
See attributes(5) for descriptions of the following attributes:
|ATTRIBUTE TYPE||ATTRIBUTE VALUE|
|MT-Level||MT-Safe with exceptions|