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

13       mblen — get number of bytes in a character
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SYNOPSIS

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

21       The functionality described on this reference page is aligned with  the
22       ISO C  standard.  Any  conflict between the requirements described here
23       and the ISO C standard is unintentional. This  volume  of  POSIX.1‐2008
24       defers to the ISO C standard.
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26       If s is not a null pointer, mblen() shall determine the number of bytes
27       constituting the character pointed to by  s.   Except  that  the  shift
28       state of mbtowc() is not affected, it shall be equivalent to:
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30           mbtowc((wchar_t *)0, s, n);
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32       The  implementation shall behave as if no function defined in this vol‐
33       ume of POSIX.1‐2008 calls mblen().
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35       The behavior of this function is affected by the LC_CTYPE  category  of
36       the current locale. For a state-dependent encoding, this function shall
37       be placed into its initial state by a  call  for  which  its  character
38       pointer  argument,  s,  is  a  null pointer. Subsequent calls with s as
39       other than a null pointer shall cause the internal state of  the  func‐
40       tion  to be altered as necessary. A call with s as a null pointer shall
41       cause this function to return a non-zero value if encodings have  state
42       dependency,  and  0  otherwise.  If  the implementation employs special
43       bytes to change the shift state, these bytes shall not produce separate
44       wide-character  codes, but shall be grouped with an adjacent character.
45       Changing the LC_CTYPE category causes the shift state of this  function
46       to be unspecified.
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48       The mblen() function need not be thread-safe.
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RETURN VALUE

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

61       The mblen() function may fail if:
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63       EILSEQ An invalid character sequence is detected.
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65       The following sections are informative.
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EXAMPLES

68       None.
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APPLICATION USAGE

71       None.
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RATIONALE

74       None.
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FUTURE DIRECTIONS

77       None.
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SEE ALSO

80       mbtowc(), mbstowcs(), wctomb(), wcstombs()
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82       The Base Definitions volume of POSIX.1‐2008, <stdlib.h>
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85       Portions of this text are reprinted and reproduced in  electronic  form
86       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
87       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
88       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
89       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
90       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
91       event of any discrepancy between this version and the original IEEE and
92       The  Open Group Standard, the original IEEE and The Open Group Standard
93       is the referee document. The original Standard can be  obtained  online
94       at http://www.unix.org/online.html .
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96       Any  typographical  or  formatting  errors that appear in this page are
97       most likely to have been introduced during the conversion of the source
98       files  to  man page format. To report such errors, see https://www.ker
99       nel.org/doc/man-pages/reporting_bugs.html .
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103IEEE/The Open Group                  2013                            MBLEN(3P)
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