функция преобразования кодового набора (codeset conversion function)
Пролог (Prolog)
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.
Имя (Name)
iconv — codeset conversion function
Синопсис (Synopsis)
#include <iconv.h>
size_t iconv(iconv_t cd, char **restrict inbuf,
size_t *restrict inbytesleft, char **restrict outbuf,
size_t *restrict outbytesleft);
Описание (Description)
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.
Возвращаемое значение (Return value)
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.
Ошибки (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.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
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.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
None.
Смотри также (See also)
iconv_open(3p), iconv_close(3p), mbsrtowcs(3p)
The Base Definitions volume of POSIX.1‐2017, iconv.h(0p)
