OOP 8 lab 1 task

#include <iostream>
#include <cmath>

#define EPS 1e-6

using namespace std;

class Comp {
    float re, im;

    public:
        Comp() {}

        Comp& operator = (const Comp &x) {
            re = x.re; im = x.im;
            return *this;
        }

        Comp &operator -= (const Comp &x) {
            re -= x.re; im -= x.im;
            return *this;
        }

        friend Comp operator + (const Comp &a, const Comp &b);

        bool operator == (const Comp &x) {
            return (this -> re == x.re && this -> im == x.im);
        }

        void set(char c);

        void get(char c);
};

int main() {

    Comp a, b, c;

    a.set('a');
    b.set('b');

    cout << endl << "Operator -=" << endl;

    cout << "before:" << endl;

    a.get('a');
    b.get('b');

    cout << endl << "after a -= b:" << endl;

    a -= b;

    a.get('a');
    b.get('b');


    cout << endl << "Operator +" << endl;

    a.get('a');
    b.get('b');

    c = a + b;

    cout << endl << "after c = a + b:" << endl;

    c.get('c');


    cout << endl << "Operator ==" << endl;

    a.get('a');
    b.get('b');

    cout << endl << "after a == b:" << endl;

    if (a == b) {
        cout << "true";
    } else {
        cout << "false";
    }

    a = b;

    cout << endl << endl << "In a assigned b:" << endl;

    cout << endl << "Operator ==" << endl;

    a.get('a');
    b.get('b');

    cout << endl << "after a == b:" << endl;

    if (a == b) {
        cout << "true";
    } else {
        cout << "false";
    }

    return 0;
}

Comp operator + (const Comp &a, const Comp &b) {
    Comp c;

    c.re = a.re + b.re; c.im = a.im + b.im;
    return c;
}

bool isZero(double x) { return fabs(x) > EPS; }

void Comp :: set(char c) {
    cout << "Enter comp number " << c << ":" << endl;
    cout << "\tre: ";
    cin >> re;
    cout << "\tim: ";
    cin >> im;

    return;
}

void Comp :: get(char c) {
    cout << "Comp number " << c << ": ";
    if (!isZero(re)) {
        cout << re;
    }

    if (!isZero(im)) {
        if (!isZero(re) && im > 0) {

            cout << " + ";
        }
        if (im < 0) {
            cout << " - ";
        }
        cout << abs(im) << "i";
    }

    cout << endl;

    return;
}