#include <wchar.h> int wcswidth(const wchar_t *pwcs, size_t n);
The wcswidth() function determines the number of column positions required for n wide-character codes (or fewer than n wide-character codes if a null wide-character code is encountered before n wide-character codes are exhausted) in the string pointed to by pwcs.
The wcswidth() function either returns 0 (if pwcs points to a null wide-character code), or returns the number of column positions to be occupied by the wide-character string pointed to by pwcs, or returns −1 (if any of the first n wide-character codes in the wide-character string pointed to by pwcs is not a printing wide-character code).
No errors are defined.
See attributes(5) for descriptions of the following attributes: