MBSRTOWCS(3) Linux Programmer's Manual MBSRTOWCS(3)
mbsrtowcs - convert a multibyte string to a wide character string
size_t mbsrtowcs(wchar_t *dest, const char **src,
size_t len, mbstate_t *ps);
If dest is not a NULL pointer, the mbsrtowcs function converts the multibyte string *src to a wide-character string starting at dest. At
most len wide characters are written to dest. The shift state *ps is updated. The conversion is effectively performed by repeatedly calling
mbrtowc(dest,*src,n,ps) where n is some positive number, as long as this call succeeds, and then incrementing dest by one and *src by the
number of bytes consumed. The conversion can stop for three reasons:
1. An invalid multibyte sequence has been encountered. In this case *src is left pointing to the invalid multibyte sequence, (size_t)(-1)
is returned, and errno is set to EILSEQ.
2. len non-L'