ICONV(3)                            Linux Programmer's Manual                            ICONV(3)



NAME
       iconv - perform character set conversion

SYNOPSIS
       #include <iconv.h>

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

DESCRIPTION
       The  iconv()  function  converts  a  sequence of characters in one character encoding to a
       sequence of characters in another character encoding.  The cd  argument  is  a  conversion
       descriptor,  previously  created  by  a  call  to iconv_open(3); the conversion descriptor
       defines the character encodings that iconv() uses for the conversion.  The inbuf  argument
       is  the  address  of  a variable that points to the first character of the input sequence;
       inbytesleft indicates the number of bytes in that buffer.   The  outbuf  argument  is  the
       address  of  a variable that points to the first byte available in the output buffer; out‐
       bytesleft indicates the number of bytes available in the output buffer.

       The main case is when inbuf is not NULL and *inbuf is not NULL.  In this case, the iconv()
       function converts the multibyte sequence starting at *inbuf to a multibyte sequence start‐
       ing at *outbuf.  At most *inbytesleft bytes, starting at *inbuf, will be  read.   At  most
       *outbytesleft bytes, starting at *outbuf, will be written.

       The  iconv()  function  converts one multibyte character at a time, and for each character
       conversion it increments *inbuf and decrements *inbytesleft by  the  number  of  converted
       input bytes, it increments *outbuf and decrements *outbytesleft by the number of converted
       output bytes, and it updates the conversion state  contained  in  cd.   If  the  character
       encoding  of  the  input  is stateful, the iconv() function can also convert a sequence of
       input bytes to an update to the conversion state without producing any output bytes;  such
       input is called a shift sequence.  The conversion can stop for four reasons:

       1. An invalid multibyte sequence is encountered in the input.  In this case, it sets errno
          to EILSEQ and returns (size_t) -1.  *inbuf is left pointing to  the  beginning  of  the
          invalid multibyte sequence.

       2. The  input  byte  sequence  has been entirely converted, that is, *inbytesleft has gone
          down to 0.  In this case, iconv() returns the number of nonreversible conversions  per‐
          formed during this call.

       3. An  incomplete  multibyte  sequence  is  encountered  in  the input, and the input byte
          sequence terminates after it.  In this case,  it  sets  errno  to  EINVAL  and  returns
          (size_t) -1.   *inbuf  is  left  pointing  to the beginning of the incomplete multibyte
          sequence.

       4. The output buffer has no more room for the next converted character.  In this case,  it
          sets errno to E2BIG and returns (size_t) -1.

       A different case is when inbuf is NULL or *inbuf is NULL, but outbuf is not NULL and *out‐
       buf is not NULL.  In this case, the iconv() function attempts to set cd's conversion state
       to  the  initial state and store a corresponding shift sequence at *outbuf.  At most *out‐
       bytesleft bytes, starting at *outbuf, will be written.  If the output buffer has  no  more
       room  for this reset sequence, it sets errno to E2BIG and returns (size_t) -1.  Otherwise,
       it increments *outbuf and decrements *outbytesleft by the number of bytes written.

       A third case is when inbuf is NULL or *inbuf is NULL, and outbuf is  NULL  or  *outbuf  is
       NULL.  In this case, the iconv() function sets cd's conversion state to the initial state.

RETURN VALUE
       The  iconv()  function  returns  the number of characters converted in a nonreversible way
       during this call; reversible conversions are not counted.  In case of error, it sets errno
       and returns (size_t) -1.

ERRORS
       The following errors can occur, among others:

       E2BIG  There is not sufficient room at *outbuf.

       EILSEQ An invalid multibyte sequence has been encountered in the input.

       EINVAL An incomplete multibyte sequence has been encountered in the input.

VERSIONS
       This function is available in glibc since version 2.1.

ATTRIBUTES
   Multithreading (see pthreads(7))
       The iconv() function is thread-safe.

CONFORMING TO
       POSIX.1-2001.

NOTES
       Although  inbuf  and outbuf are typed as char **, this does not mean that the objects they
       point can be interpreted as C strings or as arrays of characters:  the  interpretation  of
       character  byte  sequences  is  handled  internally  by the conversion functions.  In some
       encodings, a zero byte may be a valid part of a multibyte character.

       The caller of iconv() must ensure that the pointers passed to the  function  are  suitable
       for accessing characters in the appropriate character set.  This includes ensuring correct
       alignment on platforms that have tight restrictions on alignment.

SEE ALSO
       iconv_close(3), iconv_open(3), iconvconfig(8)

COLOPHON
       This page is part of release 3.74 of the Linux man-pages project.  A  description  of  the
       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at http://www.kernel.org/doc/man-pages/.



GNU                                         2014-06-13                                   ICONV(3)