1MBLEN(3P)                  POSIX Programmer's Manual                 MBLEN(3P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

12       mblen - get number of bytes in a character
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SYNOPSIS

15       #include <stdlib.h>
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17       int mblen(const char *s, size_t n);
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DESCRIPTION

21       If s is not a null pointer, mblen() shall determine the number of bytes
22       constituting the character pointed to by s. Except that the shift state
23       of mbtowc() is not affected, it shall be equivalent to:
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26              mbtowc((wchar_t *)0, s, n);
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28       The implementation shall behave as if no function defined in this  vol‐
29       ume of IEEE Std 1003.1-2001 calls mblen().
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31       The  behavior  of this function is affected by the LC_CTYPE category of
32       the current locale. For a state-dependent encoding, this function shall
33       be  placed  into  its  initial  state by a call for which its character
34       pointer argument, s, is a null pointer.  Subsequent  calls  with  s  as
35       other  than  a null pointer shall cause the internal state of the func‐
36       tion to be altered as necessary. A call with s as a null pointer  shall
37       cause  this function to return a non-zero value if encodings have state
38       dependency, and 0 otherwise.  If  the  implementation  employs  special
39       bytes to change the shift state, these bytes shall not produce separate
40       wide-character codes, but shall be grouped with an adjacent  character.
41       Changing  the LC_CTYPE category causes the shift state of this function
42       to be unspecified.
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RETURN VALUE

45       If s is a null pointer, mblen() shall return a non-zero or 0 value,  if
46       character  encodings,  respectively,  do or do not have state-dependent
47       encodings. If s is not a null pointer, mblen() shall  either  return  0
48       (if s points to the null byte), or return the number of bytes that con‐
49       stitute the character (if the next n or fewer bytes form a valid  char‐
50       acter),  or  return -1 (if they do not form a valid character)  and may
51       set errno to indicate the error.  In no case shall the  value  returned
52       be greater than n or the value of the {MB_CUR_MAX} macro.
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ERRORS

55       The mblen() function may fail if:
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57       EILSEQ Invalid character sequence is detected.
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60       The following sections are informative.
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EXAMPLES

63       None.
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APPLICATION USAGE

66       None.
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RATIONALE

69       None.
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FUTURE DIRECTIONS

72       None.
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SEE ALSO

75       mbtowc(), mbstowcs(), wctomb(), wcstombs(), the Base Definitions volume
76       of IEEE Std 1003.1-2001, <stdlib.h>
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79       Portions of this text are reprinted and reproduced in  electronic  form
80       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
81       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
82       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
83       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
84       event of any discrepancy between this version and the original IEEE and
85       The Open Group Standard, the original IEEE and The Open Group  Standard
86       is  the  referee document. The original Standard can be obtained online
87       at http://www.opengroup.org/unix/online.html .
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91IEEE/The Open Group                  2003                            MBLEN(3P)
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