The
mbsrtowcs() converts the multibyte character string indirectly pointed to by
s to the corresponding wide character string, and stores it in the array pointed to by
pwcs. The conversion stops due to the following reasons:
•
The conversion reaches a nul byte. In this case, the nul byte is also converted.
•
The mbsrtowcs() has already stored n wide characters.
•
The conversion encounters an invalid character.
Each character will be converted as if
mbrtowc(3) is continuously called.
After conversion, if
pwcs is not a null pointer, the pointer object pointed to by
s is a null pointer (if the conversion is stopped due to reaching a nul byte) or the first byte of the character just after the last character converted.
If
pwcs is not a null pointer and the conversion is stopped due to reaching a nul byte, the
mbsrtowcs() places the state object pointed to by
ps to an initial state after the conversion has taken place.
The behaviour of
mbsrtowcs() is affected by the
LC_CTYPE category of the current locale.
These are the special cases:
s == NULL || *s == NULL
Undefined (may cause the program to crash).
pwcs == NULL
The conversion has taken place, but the resulting wide character string was discarded. In this case, the pointer object pointed to by s is not modified and n is ignored.
ps == NULL
The
mbsrtowcs() uses its own internal state object to keep the conversion state, instead of
ps mentioned in this manual page.
Calling any other functions in
Standard C Library (libc, -lc) never changes the internal state of
mbsrtowcs(), which is initialized at startup time of the program.