Function push_back

src/include/nlohmann/json.hpp:3117–3138

@brief add an object to an array @sa https://json.nlohmann.me/api/basic_json/push_back/

    /// @brief add an object to an array
    /// @sa https://json.nlohmann.me/api/basic_json/push_back/
    void push_back(basic_json&& val)
    {
        // push_back only works for null objects or arrays
        if (JSON_HEDLEY_UNLIKELY(!(is_null() || is_array())))
        {
            JSON_THROW(type_error::create(308, detail::concat("cannot use push_back() with ", type_name()), this));
        }

        // transform a null object into an array
        if (is_null())
        {
            m_data.m_type = value_t::array;
            m_data.m_value = value_t::array;
            assert_invariant();
        }

        // add the element to the array (move semantics)
        const auto old_capacity = m_data.m_value.array->capacity();
        m_data.m_value.array->push_back(std::move(val));
        set_parent(m_data.m_value.array->back(), old_capacity);
        // if val is moved from, basic_json move constructor marks it null, so we do not call the destructor
    }

    /// @brief add an object to an array
    /// @sa https://json.nlohmann.me/api/basic_json/operator+=/