Do not use std::to_string

[krisztiantobias]

This is simply wrong:

    case (value_t::number_float):
    {
        return std::to_string(m_value.number_float);
    }

The to_string use std::locale what can change the point to comma (happened with us, because in QT the QApplication create change this) what is not good for json. You have to use always point instead of comma (json rpc standard)

[nlohmann]

Thanks for the hint. I'll check.

[nlohmann]

Hi @krisztiantobias,

the current code does not use std::to_string to create a serialization of floating-point numbers any more, but the following snippet (see https://github.com/nlohmann/json/blob/master/src/json.hpp.re2c#L2016):

case (value_t::number_float):
{
    // 15 digits of precision allows round-trip IEEE 754
    // string->double->string
    const auto sz = static_cast<unsigned int>(std::snprintf(nullptr, 0, "%.15g", m_value.number_float));
    std::vector<char> buf(sz + 1);
    std::snprintf(&buf[0], buf.size(), "%.15g", m_value.number_float);
    return string_t(buf.data());
}

Do you see the same issue there? If so, wouldn't prepending

std::locale::global(std::locale::classic());

fix the issue?

[krisztiantobias]

It's fix that, but very ugly I think. In our code I fix that with this:

Before dump:

template<typename CharT>
class DecimalSeparator : public std::numpunct<CharT>
{
public:
    DecimalSeparator(CharT Separator)
    : m_Separator(Separator)
    {}

protected:
    CharT do_decimal_point()const
    {
        return m_Separator;
    }

private:
    CharT m_Separator;
};

And in dump:

case (value_t::number_float):
{
    std::stringstream ss;
    ss.imbue(std::locale(std::locale(), new DecimalSeparator<char>('.')));
    ss << m_value.number_float;
    return ss.str();
}

[nlohmann]

In fact, the above code already fixed another issue (#37) and stems from #38. Therefore, I'd like to stick with it rather than changing it to to_string().