<complex>类复数相加问题，求解

#include<iostream>
#include<complex>
using namespace std;

class Complex
{
    private:
        complex <double> Complex_add;
    public:
        Complex() : Complex_add(0, 0)
        {
            cout << "Initialize!" << endl;
        }
        friend void add(Complex&, complex <double>&, complex <double>&);
        void output();
        ~Complex()
        {
            cout << "Set free!" << endl;
        }
};

void add(Complex& num, complex <double>& num1, complex <double>& num2)
{
    = num1.real() + num2.real();
    = num1.imag() + num2.imag();
}

void Complex :: output()
{
    cout << "The real is" << Complex_add.real() << endl;
    cout << "The imag is" << Complex_add.imag() << endl;
}

int main()
{
    Complex Complex_add;

    complex <double> num1(2.3, 3.4);
    complex <double> num2(4.11, 3.45);

    add(Complex_add, num1, num2);
    Complex_add.output();
   
    cout << endl;
    return 0;
}
运行之后只加了虚部
实部还是0
各位帮帮忙