wcsrtombs(3)

1wcsrtombs(3)               Library Functions Manual               wcsrtombs(3)
2
3
4

NAME

6       wcsrtombs - convert a wide-character string to a multibyte string
7

LIBRARY

9       Standard C library (libc, -lc)
10

SYNOPSIS

12       #include <wchar.h>
13
14       size_t wcsrtombs(char dest[restrict .len], const wchar_t **restrict src,
15                        size_t len, mbstate_t *restrict ps);
16

DESCRIPTION

18       If dest is not NULL, the wcsrtombs() function converts the wide-charac‐
19       ter string *src to a multibyte string starting at dest.   At  most  len
20       bytes  are  written to dest.  The shift state *ps is updated.  The con‐
21       version is effectively performed by  repeatedly  calling  wcrtomb(dest,
22       *src, ps), as long as this call succeeds, and then incrementing dest by
23       the number of bytes written and *src by one.  The conversion  can  stop
24       for three reasons:
25
26       •  A wide character has been encountered that can not be represented as
27          a multibyte sequence (according to the  current  locale).   In  this
28          case,   *src  is  left  pointing  to  the  invalid  wide  character,
29          (size_t) -1 is returned, and errno is set to EILSEQ.
30
31       •  The length limit forces a stop.  In this case, *src is left pointing
32          to  the next wide character to be converted, and the number of bytes
33          written to dest is returned.
34
35       •  The wide-character string has been completely  converted,  including
36          the  terminating null wide character (L'\0'), which has the side ef‐
37          fect of bringing back *ps to the initial state.  In this case,  *src
38          is  set  to NULL, and the number of bytes written to dest, excluding
39          the terminating null byte ('\0'), is returned.
40
41       If dest is NULL, len is ignored, and the conversion proceeds as  above,
42       except that the converted bytes are not written out to memory, and that
43       no length limit exists.
44
45       In both of the above cases, if ps is NULL,  a  static  anonymous  state
46       known only to the wcsrtombs() function is used instead.
47
48       The programmer must ensure that there is room for at least len bytes at
49       dest.
50

RETURN VALUE

52       The wcsrtombs() function returns the number of bytes that make  up  the
53       converted  part  of  multibyte  sequence, not including the terminating
54       null byte.  If a wide character was encountered which could not be con‐
55       verted, (size_t) -1 is returned, and errno set to EILSEQ.
56

ATTRIBUTES

58       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
59       tributes(7).
60
61       ┌────────────┬───────────────┬─────────────────────────────────────────┐
62       │Interface   │ Attribute     │ Value                                   │
63       ├────────────┼───────────────┼─────────────────────────────────────────┤
64       │wcsrtombs() │ Thread safety │ MT-Unsafe race:wcsrtombs/!ps            │
65       └────────────┴───────────────┴─────────────────────────────────────────┘
66

STANDARDS

68       C11, POSIX.1-2008.
69

HISTORY

71       POSIX.1-2001, C99.
72

NOTES

74       The behavior of wcsrtombs() depends on the  LC_CTYPE  category  of  the
75       current locale.
76
77       Passing NULL as ps is not multithread safe.
78