ICONV
Section: Linux Programmer's Manual (3)
Updated: 2014-06-13
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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;
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
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)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- VERSIONS
-
- ATTRIBUTES
-
- Multithreading (see pthreads(7))
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
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Time: 02:55:09 GMT, September 18, 2014