complex

#include <stdio.h>
#include <math.h>

class complex {
private:
    double r,i;
public:
    complex(void);
    complex(double,double);
    double abs(void);
    void show(void);
    complex co(void);
    //friend complex operator+(complex,complex);
    complex operator+(complex);     //c=a+b
    complex operator++(void); //prefix  ++a
    complex operator++(int); //postfix  a++
};
complex complex::operator +(complex b) {
    return complex(r+b.r,i+b.i);
}

/*complex operator+(complex a,complex b) {
    return complex(a.r+b.r,a.i+b.i);
}*/

complex complex::co(void) {
    return complex(r,-i);
}

complex::complex(void) {
    r=0;
    i=0;
}
complex::complex(double a,double b) {
    r=a;
    i=b;
}
double complex::abs(void) {
    return sqrt(r*r+i*i);
}
void complex::show(void) {
    printf("Re=%lf\nIm=%lf\n\n",r,i);
}
int main() {
    complex a(7,11),b(3,4);
    a=a+b;
    a.show();
}