Function value

3rd/nlohmann_json/include/nlohmann/json.hpp:3989–4005

                   detail::is_getable<basic_json_t, ValueType>::value
                   && !std::is_same<value_t, ValueType>::value, int >::type = 0 >
    ValueType value(const typename object_t::key_type& key, const ValueType& default_value) const
    {
        // at only works for objects
        if (JSON_HEDLEY_LIKELY(is_object()))
        {
            // if key is found, return value and given default value otherwise
            const auto it = find(key);
            if (it != end())
            {
                return it->template get<ValueType>();
            }

            return default_value;
        }

        JSON_THROW(type_error::create(306, "cannot use value() with " + std::string(type_name()), *this));
    }

    /*!
    @brief overload for a default value of type const char*