cd

    A conversion descriptor. This is returned by a successful call to
    iconv_open.

 inbuf

    A pointer to a variable that points to the first character in the
    input buffer.

 inbytesleft

    Initially, this argument is a pointer to a variable that
    indicates the number of bytes to the end of the input buffer
    (inbuf). When the conversion is completed, the variable indicates
    the number of bytes in inbuf not converted.

 outbuf

    A pointer to a variable that points to the first available byte
    in the output buffer. The output buffer contains the converted
    characters.

 outbytesleft

    Initially, this argument is a pointer to a variable that
    indicates the number of bytes to the end of the output buffer
    (outbuf). When the conversion is completed, the variable
    indicates the number of bytes left in outbuf.