operator<()

bool nlohmann::detail::operator< ( const value_t  lhs, const value_t  rhs  )

inlinenoexcept

comparison operator for JSON types

Returns an ordering that is similar to Python:

• order: null < boolean < number < object < array < string < binary
• furthermore, each type is not smaller than itself
• discarded values are not comparable
• binary is represented as a b"" string in python and directly comparable to a string; however, making a binary array directly comparable with a string would be surprising behavior in a JSON file.

Since

version 1.0.0

Definition at line 147 of file json.hpp.

{
    static constexpr std::array<std::uint8_t, 9> order = {{
            0 /* null */, 3 /* object */, 4 /* array */, 5 /* string */,
            1 /* boolean */, 2 /* integer */, 2 /* unsigned */, 2 /* float */,
            6 /* binary */
        }
    };
    const auto l_index = static_cast<std::size_t>(lhs);
    const auto r_index = static_cast<std::size_t>(rhs);
    return l_index < order.size() && r_index < order.size() && order[l_index] < order[r_index];
}