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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | ATTRIBUTES | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
ICONV(3) Linux Programmer's Manual ICONV(3)
iconv - perform character set conversion
#include <iconv.h>
size_t iconv(iconv_t cd,
char **inbuf, size_t *inbytesleft,
char **outbuf, size_t *outbytesleft);
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.
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.
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.
This function is available in glibc since version 2.1.
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.
POSIX.1-2001, POSIX.1-2008.
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.
iconv_close(3), iconv_open(3), iconvconfig(8)
This page is part of release 4.12 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)
Pages that refer to this page: iconv(1), iconv_close(3), iconv_open(3), mbsnrtowcs(3), mbsrtowcs(3), wcsnrtombs(3), wcsrtombs(3), wprintf(3), locale(7), iconvconfig(8)