NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

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

NAME         top

       iconv - perform character set conversion

SYNOPSIS         top

       #include <iconv.h>

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

DESCRIPTION         top

       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; outbytesleft 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 starting 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 performed 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 *outbuf 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
       *outbytesleft 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         top

       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         top

       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         top

       This function is available in glibc since version 2.1.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).

       ┌──────────┬───────────────┬─────────────────┐
       │Interface Attribute     Value           │
       ├──────────┼───────────────┼─────────────────┤
       │iconv()   │ Thread safety │ MT-Safe race:cd │
       └──────────┴───────────────┴─────────────────┘
       The iconv() function is MT-Safe, as long as callers arrange for
       mutual exclusion on the cd argument.

CONFORMING TO         top

       POSIX.1-2001, POSIX.1-2008.

NOTES         top

       In each series of calls to iconv(), the last should be one with inbuf
       or *inbuf equal to NULL, in order to flush out any partially
       converted input.

       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         top

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

COLOPHON         top

       This page is part of release 4.07 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
       https://www.kernel.org/doc/man-pages/.

GNU                              2015-12-28                         ICONV(3)