NAME

mbsrtowcs, mbsnrtowcs — convert a character string to a wide-character string (restartable)

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <wchar.h>

size_t
mbsrtowcs(wchar_t * restrict dst, const char ** restrict src, size_t len, mbstate_t * restrict ps);

size_t
mbsnrtowcs(wchar_t * restrict dst, const char ** restrict src, size_t nms, size_t len, mbstate_t * restrict ps);

DESCRIPTION

The mbsrtowcs() function converts a sequence of multibyte characters pointed to indirectly by src into a sequence of corresponding wide characters and stores at most len of them in the wchar_t array pointed to by dst, until it encounters a terminating null character ('\0').

If dst is NULL, no characters are stored.

If dst is not NULL, the pointer pointed to by src is updated to point to the character after the one that conversion stopped at. If conversion stops because a null character is encountered, *src is set to NULL.

The mbstate_t argument, ps, is used to keep track of the shift state. If it is NULL, mbsrtowcs() uses an internal, static mbstate_t object, which is initialized to the initial conversion state at program startup.

The mbsnrtowcs() function behaves identically to mbsrtowcs(), except that conversion stops after reading at most nms bytes from the buffer pointed to by src.

RETURN VALUES

If successful, and dst is not NULL, the mbsrtowcs() and mbsnrtowcs() functions return the number of wide characters stored in the array pointed to by dst.

If dst was NULL then the functions mbsrtowcs() and mbsnrtowcs() return the number of wide characters that would have been stored where dst points to an infinitely large array.

If either one of the functions is not successful then (size_t)-1 is returned.

ERRORS

The mbsrtowcs() and mbsnrtowcs() functions will fail if:

[EILSEQ]: An invalid multibyte character sequence was encountered.
[EINVAL]: The conversion state is invalid.

STANDARDS

The mbsrtowcs() function conforms to ISO/IEC 9899:1999 (“ISO C99”).

The mbsnrtowcs() function is an extension to the standard.