wcwidth, wcwidth_l - number of column positions of a wide-character code
int wcwidth(wchar_t wc);
int wcwidth_l(wchar_t wc, locale_t loc);
The wcwidth() function determines the number of column positions required
for the wide character wc. The value of wc must be a character
representable as a wchar_t, and must be a wide-character code
corresponding to a valid character in the current locale.
The function wcwidth_l() behaves identically to
wcwidth(), except instead of operating in the current locale, it
operates in the locale specified by loc.
These functions either return 0 (if wc is a null wide-character
code), or the number of column positions to be occupied by the wide-character
code wc, or −1 (if wc does not correspond to a
printing wide-character code).
See attributes(7) for descriptions of the following attributes:
The wcwidth() function is Standard. The wcwidth_l()
function is Uncommitted.