Arithmetic operations on Complex Numbers

I am trying to make a program that Takes two complex Numbers from User and then in Output it shows Addition, Subtraction and Multiplication Of these Numbers I have Provided mY code Below But It Does not Show Correct Output I have Tried very much But it's not working a little Help would be appreciated

  #include<iostream>
  using namespace std;
  class complexnumber
  {
    int real, image;
    public:
    {
    real = real;
    image = image;
}
complexnumber operator +(complexnumber c2)
{
    complexnumber temp;
    temp.real = real + c2.real;
    temp.image = image + c2.image;
    return temp;
}
    complexnumber operator-(complexnumber c2)
    {
        complexnumber temp;
        temp.real = real - c2.real;
        temp.image = image - c2.image;
        return temp;
    }
    complexnumber operator*(complexnumber c2)
    {
        complexnumber temp;
        temp.real = real * c2.real + (image *c2.image)*(-1);
        temp.image = image * c2.real+c2.image*real;
        return temp;
    }
    void display(complexnumber c)
    {
        if (c.image < 0)
        {
            cout << real <<  image << "i";
        }
        else
        {
            cout << real << "+" << image << "i";
        }
    }
};
int main()
{
    int real1, real2, image1, image2;
    cout << "enter real value 1:";
    cin >> real1;
    cout << endl;
    cout << "enter real value 2:";
    cin >> real2;
    cout << endl;
    cout << "enter imaginary value 1:";
    cin >> image1;
    cout << endl;
    cout << "enter imaginary value 2:";
    cin >> image2;
    cout << endl;
    complexnumber c1, c2, c3, c4, c5;
    c1.set(real1, image1);
    c2.set(real2, image2);
    c3 = c1 + c2;
    c4 = c1 - c2;
    c5=c1*c2;
    cout << "addition of two complex number       ";
    c3.display(c3);
    cout << endl;
    cout << "subtraction of two complex number    ";
    c4.display(c4);
    cout << endl;
    cout << "multiplication of two complex number ";
    c5.display(c5);
    cout << endl;
    return 0;
}