Question

when i declare ostream << overloading method in my complex number’s class ,it crushes suddenly
here it is

#include<math.h>
#include<ostream>
#include<iostream>

class complex
{

public:
    double getRe();
    double gerIm();
    void setRe(double value);
    void setIm(double value);
    explicit complex(double=0.0,double=0.0);
    static complex fromPolar(double radius,double angle);
    complex operator+(complex rhs);
    complex operator-(complex rhhs);
    complex operator*(complex rhs);
    complex operator+(double rhs);
    complex operator-(double rhs);
    complex operator*(double rhs);
    complex conjugate();
    double norm();
    complex operator/(double rhs);
    complex operator/(complex rhs);
     friend ostream &operator<<(ostream &out, complex c);
private:
    double real;
    double img;

};
 ostream &operator<<(ostream &out, complex c)
{
    out<<c.real<<"  ";
    out<<c.img<<"  ";
    return out;


}
complex operator+(double lhs,complex rhs);
complex operator-(double lhs,complex rhs);
complex operator*(double lhs,complex rhs);
complex operator/(double lhs,complex rhs);
complex exp(complex c);
inline double complex::getRe(){return real;}
inline double complex::gerIm(){ return img;}
inline void complex::setRe(double value) {  real=value;}
inline void complex::setIm(double value) { img=value;}
 inline complex::complex(double re,double im) :real(re),img(im){}
 inline   complex complex::fromPolar(double radius,double angle){

     return complex(radius*cos(angle),radius*sin(angle));

 }
 inline complex complex::operator+(complex rhs)
 {
     return complex(this->real+rhs.real,this->img+rhs.img);

 }
 inline complex complex::operator-(complex rhs)
 {
     return complex(this->real-rhs.real,this->img-rhs.img);

 }
 inline complex complex::operator*(complex rhs)
 {
     return complex(this->real*rhs.real-this->img*rhs.img,this->real*rhs.img+this->img*rhs.real);

 }
 inline complex complex::operator+(double rhs)
 {
     return complex(this->real+rhs,this->img);

 }

 inline complex complex::operator-(double rhs)
 {
     return complex(this->real-rhs,this->img);

 }
 inline complex complex::operator*(double rhs)
 {
     return complex(this->real*rhs,this->img*rhs);

 }
 inline complex complex::operator/(double rhs)
 {
     return complex(this->real/rhs,this->img/rhs);

 }
 inline complex complex::operator/(complex rhs)
 {

     return (*this)*rhs.conjugate()/rhs.norm();


 }

 inline double complex::norm()
 {
 return (this->real*this->real+this->img*this->img);
 }

 inline complex complex::conjugate()
 {

     return complex(this->real,-this->img);
 }


 inline complex operator+(double lhs,complex rhs)
 {
     return rhs+lhs;
 }

 inline complex operator-(double lhs,complex rhs)
 {
     return complex(lhs-rhs.getRe(),rhs.gerIm());

 }
 inline complex operator*(double lhs,complex rhs)
 {
     rhs*lhs;

 }

 inline complex operator/(double lhs,complex rhs)
 {
     return rhs.conjugate()*lhs/rhs.norm();

 }

error says that,it is redefinition of ostream operator,but i think that i have correctly written,so can’t understand what is going on,please help me

Answer 1

ostream is in the std namespace so in your class definition you need:

friend std::ostream &operator<<(std::ostream &out, complex c);

and the corresponding definition should look like:

std::ostream &operator<<(std::ostream &out, complex c)
{
// ...

Also, you need a return statement in one of your operator* overloads:

inline complex operator*(double lhs,complex rhs)
{
    return rhs*lhs;
}

As you are using a name identical to a standard library class template in your code you should not use using namespace std;. (Even if this weren’t the case, you should avoid using namespace std; in most situations and certainly avoid it in header files.)