MBSRTOWCS(3)		 BSD Library Functions Manual		  MBSRTOWCS(3)

NAME
     mbsrtowcs — converts a multibyte character string to a wide-character
     string (restartable)

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <wchar.h>

     size_t
     mbsrtowcs(wchar_t * restrict pwcs, const char ** restrict s, size_t n,
	 mbstate_t * restrict ps);

DESCRIPTION
     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 follow‐
     ing 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 reach‐
     ing 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 man‐
		   ual 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.

RETURN VALUES
     mbsrtowcs() returns:

     0 or positive
		   The value returned is the number of elements stored in the
		   array pointed to by pwcs, except for a terminating nul wide
		   character (if any).	If pwcs is not NULL and the value
		   returned is equal to n, the wide-character string pointed
		   to by pwcs is not nul-terminated.  If pwcs is a null
		   pointer, the value returned is the number of elements to
		   contain the whole string converted, except for a terminat‐
		   ing nul wide character.

     (size_t)-1	   The array indirectly pointed to by s contains a byte
		   sequence forming invalid character.	In this case,
		   mbsrtowcs() sets errno to indicate the error.

ERRORS
     mbsrtowcs() may cause an error in the following case:

     [EILSEQ]		The pointer pointed to by s points to an invalid or
			incomplete multibyte character.

     [EINVAL]		ps points to an invalid or uninitialized mbstate_t
			object.

SEE ALSO
     mbrtowc(3), mbstowcs(3), setlocale(3)

STANDARDS
     The mbsrtowcs() function conforms to ISO/IEC 9899/AMD1:1995 (“ISO C90,
     Amendment 1”).  The restrict qualifier is added at ISO/IEC 9899:1999
     (“ISO C99”).

BSD			       February 4, 2002				   BSD

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