wcsxfrm - wide-character string transformation
#include <wchar.h> size_t wcsxfrm(wchar_t *ws1, const wchar_t *ws2, size_t n);
The wcsxfrm() function transforms the wide-character string pointed to by ws2 and places the resulting wide-character string into the array pointed to by ws1. The transformation is such that if wcscmp() is applied to two transformed wide strings, it returns a value greater than, equal to or less than 0, corresponding to the result of wcscoll() 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 behaviour is undefined.
The wcsxfrm() function will not change the setting of errno if successful.
The wcsxfrm() function returns 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, the wcsxfrm() function returns (size_t)-1, and sets errno to indicate the error.
The wcsxfrm() function may fail if:
- The wide-character string pointed to by ws2 contains wide-character codes outside the domain of the collating sequence.
The transformation function is such that two transformed wide-character strings can be ordered by wcscmp() 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, then call wcsxfrm(), then check errno.
wcscmp(), wcscoll(), <wchar.h>.
Derived from the MSE working draft.