运算符重载实现复数的相加减

#include<iostream>
using namespace std;
class complex
{
private:
    double real;
    double imag;
public:
    complex(double r=0,double i=0):real(r),imag(i){}
    complex operator + (complex &c)
    {return complex(c.real+real,c.imag+imag);}
    complex operator - (complex &c)
    {return complex(real-c.real,imag-c.imag);}
    void display()
    {
        cout<<"该复数为"<<imag<<"i+"<<real<<endl;

    }
};

int main()
{     
    complex a(1,2);
    complex b(2,3),c(0,0);
    a.display();
    c=a-b;
    c.display();
    return 0;
}