wcsnrtombs(3)

1wcsnrtombs(3)              Library Functions Manual              wcsnrtombs(3)
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NAME

6       wcsnrtombs - convert a wide-character string to a multibyte string
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LIBRARY

9       Standard C library (libc, -lc)
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SYNOPSIS

12       #include <wchar.h>
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14       size_t wcsnrtombs(char dest[restrict .len], const wchar_t **restrict src,
15                         size_t nwc, size_t len, mbstate_t *restrict ps);
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17   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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19       wcsnrtombs():
20           Since glibc 2.10:
21               _POSIX_C_SOURCE >= 200809L
22           Before glibc 2.10:
23               _GNU_SOURCE
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DESCRIPTION

26       The  wcsnrtombs()  function  is  like the wcsrtombs(3) function, except
27       that the number of wide characters to be converted, starting  at  *src,
28       is limited to nwc.
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30       If  dest  is  not  NULL, the wcsnrtombs() function converts at most nwc
31       wide characters from the wide-character  string  *src  to  a  multibyte
32       string  starting  at dest.  At most len bytes are written to dest.  The
33       shift state *ps is updated.  The conversion is effectively performed by
34       repeatedly  calling  wcrtomb(dest, *src, ps), as long as this call suc‐
35       ceeds, and then incrementing dest by the number of  bytes  written  and
36       *src by one.  The conversion can stop for three reasons:
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38       •  A wide character has been encountered that can not be represented as
39          a multibyte sequence (according to the  current  locale).   In  this
40          case,   *src  is  left  pointing  to  the  invalid  wide  character,
41          (size_t) -1 is returned, and errno is set to EILSEQ.
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43       •  nwc wide characters have been converted without encountering a  null
44          wide  character (L'\0'), or the length limit forces a stop.  In this
45          case, *src is left pointing to the next wide character  to  be  con‐
46          verted, and the number of bytes written to dest is returned.
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48       •  The  wide-character  string has been completely converted, including
49          the terminating null wide character (which has the  side  effect  of
50          bringing  back *ps to the initial state).  In this case, *src is set
51          to NULL, and the number of bytes written to dest, excluding the ter‐
52          minating null byte ('\0'), is returned.
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54       If  dest is NULL, len is ignored, and the conversion proceeds as above,
55       except that the converted bytes are not written out to memory, and that
56       no destination length limit exists.
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58       In  both  of  the  above cases, if ps is NULL, a static anonymous state
59       known only to the wcsnrtombs() function is used instead.
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61       The programmer must ensure that there is room for at least len bytes at
62       dest.
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RETURN VALUE

65       The  wcsnrtombs() function returns the number of bytes that make up the
66       converted part of multibyte sequence,  not  including  the  terminating
67       null byte.  If a wide character was encountered which could not be con‐
68       verted, (size_t) -1 is returned, and errno set to EILSEQ.
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ATTRIBUTES

71       For an  explanation  of  the  terms  used  in  this  section,  see  at‐
72       tributes(7).
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74       ┌─────────────┬───────────────┬────────────────────────────────────────┐
75       │Interface    │ Attribute     │ Value                                  │
76       ├─────────────┼───────────────┼────────────────────────────────────────┤
77       │wcsnrtombs() │ Thread safety │ MT-Unsafe race:wcsnrtombs/!ps          │
78       └─────────────┴───────────────┴────────────────────────────────────────┘
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STANDARDS

81       POSIX.1-2008.
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NOTES

84       The  behavior  of  wcsnrtombs() depends on the LC_CTYPE category of the
85       current locale.
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87       Passing NULL as ps is not multithread safe.
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