wcrtomb(3)

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

NAME

6       wcrtomb - convert a wide character to a multibyte sequence
7

LIBRARY

9       Standard C library (libc, -lc)
10

SYNOPSIS

12       #include <wchar.h>
13
14       size_t wcrtomb(char *restrict s, wchar_t wc, mbstate_t *restrict ps);
15

DESCRIPTION

17       The  main  case for this function is when s is not NULL and wc is not a
18       null wide character (L'\0').  In this case, the wcrtomb() function con‐
19       verts  the wide character wc to its multibyte representation and stores
20       it at the beginning of the character array pointed to by s.  It updates
21       the shift state *ps, and returns the length of said multibyte represen‐
22       tation, that is, the number of bytes written at s.
23
24       A different case is when s is not NULL, but wc is a null wide character
25       (L'\0').   In this case, the wcrtomb() function stores at the character
26       array pointed to by s the shift sequence needed to bring  *ps  back  to
27       the initial state, followed by a '\0' byte.  It updates the shift state
28       *ps (i.e., brings it into the initial state), and returns the length of
29       the shift sequence plus one, that is, the number of bytes written at s.
30
31       A  third  case is when s is NULL.  In this case, wc is ignored, and the
32       function effectively returns
33
34           wcrtomb(buf, L'\0', ps)
35
36       where buf is an internal anonymous buffer.
37
38       In all of the above cases, if ps is  NULL,  a  static  anonymous  state
39       known only to the wcrtomb() function is used instead.
40

RETURN VALUE

42       The  wcrtomb()  function  returns the number of bytes that have been or
43       would have been written to the byte array at s.  If wc can not be  rep‐
44       resented  as  a  multibyte  sequence (according to the current locale),
45       (size_t) -1 is returned, and errno set to EILSEQ.
46

ATTRIBUTES

48       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
49       tributes(7).
50
51       ┌─────────────────────────┬───────────────┬────────────────────────────┐
52       │Interface                │ Attribute     │ Value                      │
53       ├─────────────────────────┼───────────────┼────────────────────────────┤
54       │wcrtomb()                │ Thread safety │ MT-Unsafe race:wcrtomb/!ps │
55       └─────────────────────────┴───────────────┴────────────────────────────┘
56

STANDARDS

58       C11, POSIX.1-2008.
59

HISTORY

61       POSIX.1-2001, C99.
62

NOTES

64       The  behavior  of  wcrtomb()  depends  on  the LC_CTYPE category of the
65       current locale.
66
67       Passing NULL as ps is not multithread safe.
68