Counts the number of Unicode chars in _l_e_n bytes of _s_r_c. Places that count in _n_c_h_a_r. _w_c_h_a_r contains 1, 2 or 4 depending on the number of bytes needed to hold the largest unicode char counted. The return value indicates whether _s_r_c is a well-formed UTF8 string.
Fontconfig version 2.6.0