iconv − perform character set conversion
const char* * inbuf, size_t * inbytesleft,
char* * outbuf, size_t * outbytesleft);
The argument cd must be a conversion descriptor created using the function iconv_open.
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 *outbytesptr by the number of = converted output bytes, and it updates the conversion state contained in = cd. 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, i.e. = *inbytesleft has gone down to 0. In this case iconv returns the number of non-reversible 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 *outbytesptr 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 non-reversible way during this call; reversible conversions are not = counted. In case of error, it sets errno and returns (iconv_t)(-1).
The following errors can occur, among others:
There is not sufficient room at *outbuf.
An invalid multibyte sequence has been encountered in the input.
An incomplete multibyte sequence has been encountered in the input.