函数作用wctomb将一个宽字符转化为多字节字符 函数返回值If wctomb converts the wide character to a multibyte character, it returns the number of bytes (which is never greater than MB_CUR_MAX) in the wide character. Ifwchar is the wide-character null character (L'\0'), wctomb returns 1. If the conversion is not possible in the current locale, wctomb returns –1.