Function append_exponent

3rd/json/include/nlohmann/json.hpp:11824–11863

! @brief appends a decimal representation of e to buf @return a pointer to the element following the exponent. @pre -1000 < e < 1000 */

@pre -1000 < e < 1000
*/
inline char* append_exponent(char* buf, int e)
{
    assert(e > -1000);
    assert(e <  1000);

    if (e < 0)
    {
        e = -e;
        *buf++ = '-';
    }
    else
    {
        *buf++ = '+';
    }

    auto k = static_cast<std::uint32_t>(e);
    if (k < 10)
    {
        // Always print at least two digits in the exponent.
        // This is for compatibility with printf("%g").
        *buf++ = '0';
        *buf++ = static_cast<char>('0' + k);
    }
    else if (k < 100)
    {
        *buf++ = static_cast<char>('0' + k / 10);
        k %= 10;
        *buf++ = static_cast<char>('0' + k);
    }
    else
    {
        *buf++ = static_cast<char>('0' + k / 100);
        k %= 100;
        *buf++ = static_cast<char>('0' + k / 10);
        k %= 10;
        *buf++ = static_cast<char>('0' + k);
    }

    return buf;
}

/*!
@brief prettify v = buf * 10^decimal_exponent