mbstowcs(3)mbstowcs(3)NAME
mbstowcs, mbsrtowcs - Convert a multibyte character string to a wide-
character string
SYNOPSIS
#include <stdlib.h>
size_t mbstowcs(
wchar_t *pwcs,
const char *s,
size_t n ); #include <wchar.h>
size_t mbsrtowcs(
wchar_t *pwcs,
const char **s,
size_t n,
mbstate_t *ps );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
mbstowcs(), mbsrtowcs(): XSH5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Points to the array where the result of the conversion is stored.
Points or indirectly points to the multibyte-character string to be
converted. Specifies the number of wide characters in the destination
array. Points to an mbstate_t structure containing the conversion
state of the multibyte character in s (for mbrtowc() only).
DESCRIPTION
The mbstowcs() function converts a multibyte-character string into a
wide-character string, which is stored at a specified location. The
function does not examine or convert any characters that follow a null
byte, which is converted and stored as a wide-character code with value
zero. The function does not store more than n wide characters in pwcs.
When operating on overlapping strings, the behavior of this function is
undefined.
Behavior of the mbstowcs() function is affected by the LC_CTYPE cate‐
gory of the current locale. In locales that use shift-state encoding,
the array pointed to by the s parameter begins in the initial shift
state.
The mbsrtowcs() function is a restartable version of mbstowcs().
Restartable conversion functions obtain and store the conversion state
in an mbstate_t structure that can be read and changed by subsequent
calls to the same or other restartable conversion functions.
RESTRICTIONS
[Tru64 UNIX] The mbsrtowcs() and other restartable versions of conver‐
sion functions are functional only when used with locales that support
shift-state encoding. Currently, the operating system does not provide
any locales that support shift-state encoding, so the mbstowcs() and
mbsrtowcs() functions do not differ in terms of run-time behavior.
RETURN VALUES
When the mbstowcs() and mbsrtowcs() functions encounter an invalid
multibyte character during conversion, they return a value of -1 cast
to size_t and set errno to indicate the error. Otherwise: The
mbstowcs() function returns the number of characters stored in the out‐
put array (or required if pwcs is null), not including a terminating
null wide character, if any. When the return value is n, the output
array is not null-terminated. The mbsrtowcs() function returns the
number of characters stored in the output array, not including a termi‐
nating null wide character, if any.
ERRORS
If the following condition occurs, the mbstowcs() and mbsrtowcs() func‐
tions set errno to the corresponding value: The s parameter contains an
invalid multibyte character.
SEE ALSO
Functions: btowc(3), mblen(3), mbsinit(3), mbtowc(3), wcstombs(3),
wcslen(3), wctob(3), wctomb(3)mbstowcs(3)