ICONV(3) GNU ICONV(3)
Linux Programmer's Manual Linux Programmer's Manual
March 31, 2007
NAME
iconv - perform character set conversion
SYNOPSIS
#include <iconv.h>
size_t iconv (iconv_t cd,
const char* * inbuf, size_t * inbytesleft,
char* * outbuf, size_t * outbytesleft);
DESCRIPTION
The argument cd must be a conversion descriptor created using the
function iconv_open.
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. 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, i.e.
*inbytesleft has gone down to 0. In this case iconv returns the number
of non-reversible 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
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ICONV(3) GNU ICONV(3)
Linux Programmer's Manual Linux Programmer's Manual
March 31, 2007
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
non-reversible 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.
CONFORMING TO
POSIX:2001
SEE ALSO
iconv_open(3), iconvctl(3) iconv_close(3)
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