Overloading operators C++, complex numbers? - c++

Question

I have so big problem. I write a program which is about complex numbers. This program read and write complex numbers, add them, etc.
He said that I should read that Why should I overload a C++ operator as a global function (STL does) and what are the caveats? and
1) I must create 5 operators which are member function of class and which have one argument: +, −, !, ++, −−. Then
2) I must create 5 operators which are member function of class and which two arguments: =,+=, −=, *=, /=; Then
3) I must create 8 operators which are global friend function +, −, *, /, ==, !=, <<, >> and take two parameters. I have no problem with the last one:
friend const Comp operator+(const Comp& x, const Comp& y)
{
Comp temp;
temp.real = x.real + y.real;
temp.imag = x.imag + y.imag;
return temp;
}
friend const Comp operator-(const Comp& x, const Comp& y)
{
Comp temp;
temp.real = x.real - y.real;
temp.imag = x.imag - y.imag;
return temp;
}
friend const Comp operator*(const Comp& x, const Comp& y)
{
Comp temp;
temp.real = x.real * y.real;
temp.imag = x.imag * y.imag;
return temp;
}
friend const Comp operator/(const Comp& x, const Comp& y)
{
Comp temp;
temp.real = x.real / y.real;
temp.imag = x.imag / y.imag;
return temp;
}
except this?????? What I should return here????? When I compare It should be bool yeah????
friend const Comp operator==(const Comp& x, const Comp& y)
{
}
friend const Comp operator!=(const Comp& x, const Comp& y)
{
}
I think that I found solution
friend bool operator==(const Comp& x, const Comp& y)
{
return (x.real == y.real && x.imag == y.imag);
}
friend bool operator!=(const Comp& x, const Comp& y)
{
return (x.real != y.real && x.imag != y.imag);
}
This is my whole code
#include <fstream>
#include <cstdlib>
#include <iostream>
#include <iomanip>
#include <cmath>
#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif
using namespace std;
class Comp {
double real, imag;
public:
Comp(){
real;
imag;
}
double re(void) const
{
return real;
}
double im(void) const
{
return imag;
}
double mod(void) const
{
return sqrt(re()*re() + im()*im());
}
double arg(void) const
{
double faza;
if (im() >= 0)
faza = acos(re()/mod());
else
faza = 2*M_PI - acos(re()/mod());
return faza;
}
const Comp conj(void) const
{
Comp temp;
-im();
return temp;
}
~Comp(){}
/*
Comp operator+(const Comp& x);
Comp operator-(const Comp& x);
bool operator!(void);
const Comp& operator++();
const Comp operator++(int);
const Comp& operator--();
const Comp operator--(int);
Comp operator=(const Comp x);
Comp operator-=(const Comp& x);
Comp operator+=(const Comp& x);
Comp operator*=(const Comp& x);
Comp operator/=(const Comp& x);
*/
friend const Comp operator+(const Comp& x, const Comp& y)
{
Comp temp;
temp.real = x.real + y.real;
temp.imag = x.imag + y.imag;
return temp;
}
friend const Comp operator-(const Comp& x, const Comp& y)
{
Comp temp;
temp.real = x.real - y.real;
temp.imag = x.imag - y.imag;
return temp;
}
friend const Comp operator*(const Comp& x, const Comp& y)
{
Comp temp;
temp.real = x.real * y.real;
temp.imag = x.imag * y.imag;
return temp;
}
friend const Comp operator/(const Comp& x, const Comp& y)
{
Comp temp;
temp.real = x.real / y.real;
temp.imag = x.imag / y.imag;
return temp;
}
friend const Comp operator==(const Comp& x, const Comp& y)
{
Comp temp;
temp.real = x.real + y.real;
temp.imag = x.imag + y.imag;
return temp;
}
friend const Comp operator!=(const Comp& x, const Comp& y)
{
Comp temp;
temp.real = x.real + y.real;
temp.imag = x.imag + y.imag;
return temp;
}
friend std::ostream& operator<<(std::ostream& wart1, const Comp& a)
{
return wart1 <<fixed << setprecision(2) << '(' << a.re() << "," << a.im() << ')' << ' ' << endl;
}
friend std::istream& operator>>(std::istream& wart2, Comp& b){
char c;
return wart2>>c>>b.real>>c>>b.imag>>c;
}
};
int main(int argc, char* argv[])
{
ifstream read(argv[1]);
if (!read)
{ cerr << "Open error: " << argv[1] << endl; exit(1);}
ofstream write(argv[2]);
if(!write) { cerr << "Open error: " << argv[2] << endl; exit(2);}
read.clear();
read.seekg(0);
Comp x1;
read >> x1;
write << x1;
cout << x1;
Comp x2;
read >> x2;
write << x2;
cout << x2;
cout << x1.mod() << endl;
cout << x2.mod() << endl;
cout << x1.arg() << endl;
cout << x2.arg() << endl;
cout << x1.conj();
cout << x2.conj();
write << x2;
write << x1.mod() << endl;
write << x2.mod() << endl;
write << x1.arg() << endl;
write << x2.arg() << endl;
write << x1.conj();
write << x2.conj();
Comp sum;
sum = x1 + x2;
cout << sum;
write << sum;
Comp sub;
sub = x1 - x2;
cout << sub;
write << sub;
Comp mult;
mult = x1 * x2;
cout << mult;
write << mult;
Comp div;
div = x1 / x2;
cout << div;
write << div;
return 0;
}

Answer 1

If you implement operator== correctly (which you did in your block titled "I think that I found solution"), then you can leverage it for operator!=:
friend bool operator!=(const Comp& x, const Comp& y)
{
return !(x == y);
}
Your version was incorrect since it would report that they are not unequal if they had the same real part and a different imaginary part.
Also, in part (1) it refers to unary + and - (not binary versions which we get in part 3). So your first two declarations in the commented-out block are incorrect, they should be:
Comp operator+();
Comp operator-();