ICONV(3P)                                           POSIX Programmer's Manual                                          ICONV(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       iconv - codeset conversion function

SYNOPSIS
       #include <iconv.h>

       size_t iconv(iconv_t cd, char **restrict inbuf,
              size_t *restrict inbytesleft, char **restrict outbuf,
              size_t *restrict outbytesleft);


DESCRIPTION
       The  iconv()  function shall convert the sequence of characters from one codeset, in the array specified by inbuf, into a
       sequence of corresponding characters in another codeset, in the array specified by outbuf. The codesets are those  speci-
       fied  in  the iconv_open() call that returned the conversion descriptor, cd. The inbuf argument points to a variable that
       points to the first character in the input buffer and inbytesleft indicates the number of bytes to the end of the  buffer
       to  be  converted.  The outbuf argument points to a variable that points to the first available byte in the output buffer
       and outbytesleft indicates the number of the available bytes to the end of the buffer.

       For state-dependent encodings, the conversion descriptor cd is placed into its initial shift state by a  call  for  which
       inbuf  is  a null pointer, or for which inbuf points to a null pointer. When iconv() is called in this way, and if outbuf
       is not a null pointer or a pointer to a null pointer, and outbytesleft points to a positive value, iconv()  shall  place,
       into the output buffer, the byte sequence to change the output buffer to its initial shift state. If the output buffer is
       not large enough to hold the entire reset sequence, iconv() shall fail and set errno to [E2BIG].  Subsequent  calls  with
       inbuf  as  other  than  a null pointer or a pointer to a null pointer cause the conversion to take place from the current
       state of the conversion descriptor.

       If a sequence of input bytes does not form a valid character in the specified codeset, conversion shall  stop  after  the
       previous  successfully converted character. If the input buffer ends with an incomplete character or shift sequence, con-
       version shall stop after the previous successfully converted bytes. If the output buffer is not large enough to hold  the
       entire  converted  input, conversion shall stop just prior to the input bytes that would cause the output buffer to over-
       flow. The variable pointed to by inbuf shall be updated to point to the byte following the last byte successfully used in
       the  conversion.  The  value pointed to by inbytesleft shall be decremented to reflect the number of bytes still not con-
       verted in the input buffer. The variable pointed to by outbuf shall be updated to point to the byte  following  the  last
       byte  of  converted output data. The value pointed to by outbytesleft shall be decremented to reflect the number of bytes
       still available in the output buffer. For state-dependent encodings,  the  conversion  descriptor  shall  be  updated  to
       reflect the shift state in effect at the end of the last successfully converted byte sequence.

       If  iconv() encounters a character in the input buffer that is valid, but for which an identical character does not exist
       in the target codeset, iconv() shall perform an implementation-defined conversion on this character.

RETURN VALUE
       The iconv() function shall update the variables pointed to by the arguments to reflect the extent of the  conversion  and
       return  the  number  of  non-identical  conversions performed. If the entire string in the input buffer is converted, the
       value pointed to by inbytesleft shall be 0. If the input conversion is stopped due to any conditions mentioned above, the
       value  pointed  to by inbytesleft shall be non-zero and errno shall be set to indicate the condition. If an error occurs,
       iconv() shall return (size_t)-1 and set errno to indicate the error.

ERRORS
       The iconv() function shall fail if:

       EILSEQ Input conversion stopped due to an input byte that does not belong to the input codeset.

       E2BIG  Input conversion stopped due to lack of space in the output buffer.

       EINVAL Input conversion stopped due to an incomplete character or shift sequence at the end of the input buffer.


       The iconv() function may fail if:

       EBADF  The cd argument is not a valid open conversion descriptor.


       The following sections are informative.

EXAMPLES
       None.

APPLICATION USAGE
       The inbuf argument indirectly points to the memory area which contains the conversion input  data.  The  outbuf  argument
       indirectly  points to the memory area which is to contain the result of the conversion. The objects indirectly pointed to
       by inbuf and outbuf are not restricted to containing data that is directly representable in the ISO C  standard  language
       char  data  type.  The  type  of inbuf and outbuf, char **, does not imply that the objects pointed to are interpreted as
       null-terminated C strings or arrays of characters.  Any interpretation of a byte sequence that represents a character  in
       a  given character set encoding scheme is done internally within the codeset converters. For example, the area pointed to
       indirectly by inbuf and/or outbuf can contain all zero octets that are not interpreted as string terminators but as coded
       character  data according to the respective codeset encoding scheme. The type of the data ( char, short, long, and so on)
       read or stored in the objects is not specified, but may be inferred for both the input and output data by the  converters
       determined by the fromcode and tocode arguments of iconv_open().

       Regardless  of  the data type inferred by the converter, the size of the remaining space in both input and output objects
       (the intbytesleft and outbytesleft arguments) is always measured in bytes.

       For implementations that support the conversion of state-dependent encodings, the conversion descriptor must be  able  to
       accurately  reflect  the  shift-state in effect at the end of the last successful conversion. It is not required that the
       conversion descriptor itself be updated, which would require it to be a pointer type. Thus, implementations are  free  to
       implement  the descriptor as a handle (other than a pointer type) by which the conversion information can be accessed and
       updated.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       iconv_open(), iconv_close(), the Base Definitions volume of IEEE Std 1003.1-2001, <iconv.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy  between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard  is  the  referee   document.   The   original   Standard   can   be   obtained   online   at   http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                     ICONV(3P)