C++复数运算 重载

#include <iostream>
/*
#include <conio.h>
#include<stdio.h>
#include<iomanip>
#include<string>
#include<sstream>
*/
using namespace std;

class complex
{
    double real,imag;
public:
    complex(double,double);
    void disp(char *);
    friend complex operator + (complex,complex);
    friend complex operator - (complex,complex);
    friend complex operator * (complex,complex);
    friend complex operator / (complex,complex);
};

complex::complex (double r=0,double i=0)
{
    real = r;
    imag = i;
}

void complex::disp (char *str)
{
    cout.unsetf(ios::showpos);
    cout<<str<<"="<<real;
    if (imag)
    {
        cout.setf(ios::showpos);
        cout<<imag<<‘i‘;
    }
    cout<<endl;
    cout.unsetf(ios::showpos);
}

complex operator + (complex cpl1,complex cpl2)
{
    double t=cpl1.real+cpl2.real;
    double i=cpl1.imag+cpl2.imag;
    return complex(t,i);
}

complex operator - (complex cpl1,complex cpl2)
{
    double t=cpl1.real-cpl2.real;
    double i=cpl1.imag-cpl2.imag;
    return complex(t,i);
}

complex operator * (complex cpl1,complex cpl2)
{
    double t=cpl1.real*cpl2.real - cpl1.imag*cpl2.imag;
    double i=cpl1.real*cpl2.imag + cpl1.imag*cpl2.real;
    return complex(t,i);
}

complex operator / (complex cpl1,complex cpl2)
{
    double t=(cpl1.real*cpl2.real+cpl1.imag*cpl2.imag)/(cpl2.real*cpl2.real+cpl2.imag*cpl2.imag);
    double i=(cpl1.imag*cpl2.real-cpl1.real*cpl2.imag)/(cpl2.real*cpl2.real+cpl2.imag*cpl2.imag);
    return complex(t,i);
}

int main(void)
{
    complex c1(25,40),c2(100,200),c3(0);
    c1.disp("c1");
    c2.disp("c2");
    c3=c1+c2;
    c3.disp("c3");
    c3=c1-c3;
    c3.disp("c3");
    c3=c1*c2;
    c3.disp("c3");
    c3=c1/c2;
    c3.disp("c3");
    getchar();
    return 0;
}