MBSRTOWCS(3C) Standard C Library Functions MBSRTOWCS(3C)

NAME

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

SYNOPSIS

#include <wchar.h>

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

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

#include <wchar.h>
#include <xlocale.h>

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

size_t mbsrtowcs_l(wchar_t *restrict dst, const char **restrict src,
size_t len, mbstate_t *restrict ps, locale_t loc);

DESCRIPTION

These function converts a sequence of characters, beginning in the
conversion state described by the object pointed to by ps, from the array
indirectly pointed to by src into a sequence of corresponding wide-
characters. If dst is not a null pointer, the converted characters are
stored into the array pointed to by dst. Conversion continues up to and
including a terminating null character, which is also stored. Conversion
stops early in either of the following cases:

o When a sequence of bytes is encountered that does not form a
valid character.

o When len codes have been stored into the array pointed to by
dst (and dst is not a null pointer).

Each conversion takes place as if by a call to the mbrtowc() function.

If dst is not a null pointer, the pointer object pointed to by src is
assigned either a null pointer (if conversion stopped due to reaching a
terminating null character) or the address just past the last character
converted (if any). If conversion stopped due to reaching a terminating
null character, and if dst is not a null pointer, the resulting state
described is the initial conversion state.

If ps is a null pointer, these functions uses their own internal
mbstate_t object, which is initialized at program startup to the initial
conversion state. Otherwise, the mbstate_t object pointed to by ps is
used to completely describe the current conversion state of the
associated character sequence. The system will behave as if no function
defined in the Reference Manual calls any of these functions.

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

The behavior of mbnrtowcs() and mbsrtowcs() functions are affected by the
LC_CTYPE category of the current locale. See environ(7). The functions
mbsrtowcs_l() and mbsnrtowcs_l() behave identically to mbsrtowcs() and
mbsnrtowcs(), except that instead of using the current locale, they use
the locale specified by loc.

RETURN VALUES

If the input conversion encounters a sequence of bytes that do not form a
valid character, an encoding error occurs. In this case, these functions
store the value of the macro EILSEQ in errno and return (size_t)-1; the
conversion state is undefined. Otherwise, they return the number of
characters successfully converted, not including the terminating null (if
any).

ERRORS

These functions may fail if:

EINVAL
The ps argument points to an object that contains an invalid
conversion state.


EILSEQ
Invalid character sequence is detected.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:

+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | See below. |
+--------------------+-----------------+
|MT-Level | See below. |
+--------------------+-----------------+

The mbsnrtowcs() and mbsrtowcs() functions are Standard. The
mbsnrtowcs_l() and mbsrtowcs_l() functions are Uncommitted.

If ps is not a null pointer, these functions use the mbstate_t object
pointed to by ps and can be used safely in multithreaded applications,
otherwise they use an internal mbstate_t object and are Unsafe in
multithreaded applications.

SEE ALSO

mbrtowc(3C), mbsinit(3C), newlocale(3C), setlocale(3C), uselocale(),
attributes(7), environ(7), standards(7)


December 28, 2020 MBSRTOWCS(3C)