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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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ICONV(3P) POSIX Programmer's Manual ICONV(3P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
iconv — codeset conversion function
#include <iconv.h>
size_t iconv(iconv_t cd, char **restrict inbuf,
size_t *restrict inbytesleft, char **restrict outbuf,
size_t *restrict outbytesleft);
The iconv() function shall convert the sequence of characters from
one codeset, in the array specified by inbuf, into a sequence of
corresponding characters in another codeset, in the array
specified by outbuf. The codesets are those specified in the
iconv_open() call that returned the conversion descriptor, cd.
The inbuf argument points to a variable that points to the first
character in the input buffer and inbytesleft indicates the number
of bytes to the end of the buffer to be converted. The outbuf
argument points to a variable that points to the first available
byte in the output buffer and outbytesleft indicates the number of
the available bytes to the end of the buffer.
For state-dependent encodings, the conversion descriptor cd is
placed into its initial shift state by a call for which inbuf is a
null pointer, or for which inbuf points to a null pointer. When
iconv() is called in this way, and if outbuf is not a null pointer
or a pointer to a null pointer, and outbytesleft points to a
positive value, iconv() shall place, into the output buffer, the
byte sequence to change the output buffer to its initial shift
state. If the output buffer is not large enough to hold the entire
reset sequence, iconv() shall fail and set errno to [E2BIG].
Subsequent calls with inbuf as other than a null pointer or a
pointer to a null pointer cause the conversion to take place from
the current state of the conversion descriptor.
If a sequence of input bytes does not form a valid character in
the specified codeset, conversion shall stop after the previous
successfully converted character. If the input buffer ends with an
incomplete character or shift sequence, conversion shall stop
after the previous successfully converted bytes. If the output
buffer is not large enough to hold the entire converted input,
conversion shall stop just prior to the input bytes that would
cause the output buffer to overflow. The variable pointed to by
inbuf shall be updated to point to the byte following the last
byte successfully used in the conversion. The value pointed to by
inbytesleft shall be decremented to reflect the number of bytes
still not converted in the input buffer. The variable pointed to
by outbuf shall be updated to point to the byte following the last
byte of converted output data. The value pointed to by
outbytesleft shall be decremented to reflect the number of bytes
still available in the output buffer. For state-dependent
encodings, the conversion descriptor shall be updated to reflect
the shift state in effect at the end of the last successfully
converted byte sequence.
If iconv() encounters a character in the input buffer that is
valid, but for which an identical character does not exist in the
target codeset, iconv() shall perform an implementation-defined
conversion on this character.
The iconv() function shall update the variables pointed to by the
arguments to reflect the extent of the conversion and return the
number of non-identical conversions performed. If the entire
string in the input buffer is converted, the value pointed to by
inbytesleft shall be 0. If the input conversion is stopped due to
any conditions mentioned above, the value pointed to by
inbytesleft shall be non-zero and errno shall be set to indicate
the condition. If an error occurs, iconv() shall return (size_t)-1
and set errno to indicate the error.
The iconv() function shall fail if:
EILSEQ Input conversion stopped due to an input byte that does not
belong to the input codeset.
E2BIG Input conversion stopped due to lack of space in the output
buffer.
EINVAL Input conversion stopped due to an incomplete character or
shift sequence at the end of the input buffer.
The iconv() function may fail if:
EBADF The cd argument is not a valid open conversion descriptor.
The following sections are informative.
None.
The inbuf argument indirectly points to the memory area which
contains the conversion input data. The outbuf argument indirectly
points to the memory area which is to contain the result of the
conversion. The objects indirectly pointed to by inbuf and outbuf
are not restricted to containing data that is directly
representable in the ISO C standard language char data type. The
type of inbuf and outbuf, char **, does not imply that the objects
pointed to are interpreted as null-terminated C strings or arrays
of characters. Any interpretation of a byte sequence that
represents a character in a given character set encoding scheme is
done internally within the codeset converters. For example, the
area pointed to indirectly by inbuf and/or outbuf can contain all
zero octets that are not interpreted as string terminators but as
coded character data according to the respective codeset encoding
scheme. The type of the data (char, short, long, and so on) read
or stored in the objects is not specified, but may be inferred for
both the input and output data by the converters determined by the
fromcode and tocode arguments of iconv_open().
Regardless of the data type inferred by the converter, the size of
the remaining space in both input and output objects (the
intbytesleft and outbytesleft arguments) is always measured in
bytes.
For implementations that support the conversion of state-dependent
encodings, the conversion descriptor must be able to accurately
reflect the shift-state in effect at the end of the last
successful conversion. It is not required that the conversion
descriptor itself be updated, which would require it to be a
pointer type. Thus, implementations are free to implement the
descriptor as a handle (other than a pointer type) by which the
conversion information can be accessed and updated.
None.
None.
iconv_open(3p), iconv_close(3p), mbsrtowcs(3p)
The Base Definitions volume of POSIX.1‐2017, iconv.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard,
the original IEEE and The Open Group Standard is the referee
document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 ICONV(3P)
Pages that refer to this page: iconv.h(0p), iconv_close(3p), iconv_open(3p), mbsrtowcs(3p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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