dump() convert strings encoded by utf-8 to shift-jis on windows 10.

[silverist]

when I dump() a json object as follows, the dumped string is converted from "utf-8" to "shift-jis".
How can I do to keep up its encode "utf-8"?

{
   "data":"[[0,1,2,3,4],[0,1,2,3,4]]",
   "status":1
}

[nlohmann]

What do you mean? What output do you expect?

[silverist]

sorry, the type of "data" element is not "array" but "string".
(And the string is encoced by "utf-8".)

As the source of json.hpp, dump() seems to call the method at line 4716.
Then, execute the following section because the type of "data" element is "string", I think.
And I guess the "data" string is converted from "utf-8" to "shift-jis" when execute the following section.
(in other words, converted by std::ostream& o or escape_string function)

            case (value_t::string):
            {
                o << string_t("\"") << escape_string(*m_value.string) << "\"";
                return;
            }

■dump() in json.hpp at line 4716

    void dump(std::ostream& o, const bool pretty_print, const unsigned int indent_step,
              const unsigned int current_indent = 0) const
    {
        // variable to hold indentation for recursive calls
        unsigned int new_indent = current_indent;

        switch (m_type)
        {
            case (value_t::object):
            {
                if (m_value.object->empty())
                {
                    o << "{}";
                    return;
                }

                o << "{";

                // increase indentation
                if (pretty_print)
                {
                    new_indent += indent_step;
                    o << "\n";
                }

                for (auto i = m_value.object->cbegin(); i != m_value.object->cend(); ++i)
                {
                    if (i != m_value.object->cbegin())
                    {
                        o << (pretty_print ? ",\n" : ",");
                    }
                    o << string_t(new_indent, ' ') << "\""
                      << escape_string(i->first) << "\":"
                      << (pretty_print ? " " : "");
                    i->second.dump(o, pretty_print, indent_step, new_indent);
                }

                // decrease indentation
                if (pretty_print)
                {
                    new_indent -= indent_step;
                    o << "\n";
                }

                o << string_t(new_indent, ' ') + "}";
                return;
            }

            case (value_t::array):
            {
                if (m_value.array->empty())
                {
                    o << "[]";
                    return;
                }

                o << "[";

                // increase indentation
                if (pretty_print)
                {
                    new_indent += indent_step;
                    o << "\n";
                }

                for (auto i = m_value.array->cbegin(); i != m_value.array->cend(); ++i)
                {
                    if (i != m_value.array->cbegin())
                    {
                        o << (pretty_print ? ",\n" : ",");
                    }
                    o << string_t(new_indent, ' ');
                    i->dump(o, pretty_print, indent_step, new_indent);
                }

                // decrease indentation
                if (pretty_print)
                {
                    new_indent -= indent_step;
                    o << "\n";
                }

                o << string_t(new_indent, ' ') << "]";
                return;
            }

            case (value_t::string):
            {
                o << string_t("\"") << escape_string(*m_value.string) << "\"";
                return;
            }

            case (value_t::boolean):
            {
                o << (m_value.boolean ? "true" : "false");
                return;
            }

            case (value_t::number_integer):
            {
                o << m_value.number_integer;
                return;
            }

            case (value_t::number_float):
            {
                // 15 digits of precision allows round-trip IEEE 754
                // string->double->string; to be safe, we read this value from
                // std::numeric_limits<number_float_t>::digits10
                o << std::setprecision(std::numeric_limits<number_float_t>::digits10) << m_value.number_float;
                return;
            }

            case (value_t::discarded):
            {
                o << "<discarded>";
                return;
            }

            default:
            {
                o << "null";
                return;
            }
        }
    }

[nlohmann]

There are quotes around the array. Therefore, it is treated as string.

[silverist]

After all, I misunderstood.
I checked the data which do dump() by hex editor, it is not converted.

The reason why it seems to be converted is that a return value which "char* " points seems to lose when a function exit.
I copy the value which "char* " points by memcpy(), and return the destination value.
Then the return value do not lose, and my problem has been resolved.

Thanks all.