Convert string from UTF-8 to ISO-8859-1

Question

I'm trying to convert a UTF-8 string to a ISO-8859-1 char* for use in legacy code. The only way I'm seeing to do this is with iconv.

I would definitely prefer a completely string-based C++ solution then just call .c_str() on the resulting string.

How do I do this? Code example if possible, please. I'm fine using iconv if it is the only solution you know.

Answer 1

I'm going to modify my code from another answer to implement the suggestion from Alf.

std::string UTF8toISO8859_1(const char * in)
{
    std::string out;
    if (in == NULL)
        return out;

    unsigned int codepoint;
    while (*in != 0)
    {
        unsigned char ch = static_cast<unsigned char>(*in);
        if (ch <= 0x7f)
            codepoint = ch;
        else if (ch <= 0xbf)
            codepoint = (codepoint << 6) | (ch & 0x3f);
        else if (ch <= 0xdf)
            codepoint = ch & 0x1f;
        else if (ch <= 0xef)
            codepoint = ch & 0x0f;
        else
            codepoint = ch & 0x07;
        ++in;
        if (((*in & 0xc0) != 0x80) && (codepoint <= 0x10ffff))
        {
            if (codepoint <= 255)
            {
                out.append(1, static_cast<char>(codepoint));
            }
            else
            {
                // do whatever you want for out-of-bounds characters
            }
        }
    }
    return out;
}

Invalid UTF-8 input results in dropped characters.