Unsigned integer as UTF-8 value

Question

assuming that I have

uint32_t a(3084);

I would like to create a string that stores the unicode character U+3084 which means that I

Answer 1

Here's some C++ code that wouldn't be hard to convert to C. Adapted from an older answer.

std::string UnicodeToUTF8(unsigned int codepoint)
{
    std::string out;

    if (codepoint <= 0x7f)
        out.append(1, static_cast(codepoint));
    else if (codepoint <= 0x7ff)
    {
        out.append(1, static_cast(0xc0 | ((codepoint >> 6) & 0x1f)));
        out.append(1, static_cast(0x80 | (codepoint & 0x3f)));
    }
    else if (codepoint <= 0xffff)
    {
        out.append(1, static_cast(0xe0 | ((codepoint >> 12) & 0x0f)));
        out.append(1, static_cast(0x80 | ((codepoint >> 6) & 0x3f)));
        out.append(1, static_cast(0x80 | (codepoint & 0x3f)));
    }
    else
    {
        out.append(1, static_cast(0xf0 | ((codepoint >> 18) & 0x07)));
        out.append(1, static_cast(0x80 | ((codepoint >> 12) & 0x3f)));
        out.append(1, static_cast(0x80 | ((codepoint >> 6) & 0x3f)));
        out.append(1, static_cast(0x80 | (codepoint & 0x3f)));
    }
    return out;
}