wcslen - determine the length of a wide-character string
Standard C library (libc, -lc)
#include <wchar.h>
size_t wcslen(const wchar_t *s);
The wcslen() function returns the number of wide
characters in s.
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value | 
wcslen()  | 
Thread safety | MT-Safe | 
C11, POSIX.1-2008.
POSIX.1-2001, C99.
In cases where the input buffer may not contain a terminating null wide character, wcsnlen(3) should be used instead.
strlen(3)