iconv(3) — Linux manual page

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 5.10 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                            2017-09-15                       ICONV(3)

Pages that refer to this page: iconv(1)preconv(1)iconv_close(3)iconv_open(3)mbsnrtowcs(3)mbsrtowcs(3)wcsnrtombs(3)wcsrtombs(3)wprintf(3)locale(7)iconvconfig(8)