c 2b 2b overloaded equality check operator

1#include <iostream>
2#include <string>
3 
4class Car
5{
6private:
7    std::string m_make;
8    std::string m_model;
9 
10public:
11    Car(const std::string& make, const std::string& model)
12        : m_make{ make }, m_model{ model }
13    {
14    }
15 
16    friend bool operator== (const Car &c1, const Car &c2);
17    friend bool operator!= (const Car &c1, const Car &c2);
18};
19 
20bool operator== (const Car &c1, const Car &c2)
21{
22    return (c1.m_make== c2.m_make &&
23            c1.m_model== c2.m_model);
24}
25 
26bool operator!= (const Car &c1, const Car &c2)
27{
28    return !(c1== c2);
29}
30 
31int main()
32{
33    Car corolla{ "Toyota", "Corolla" };
34    Car camry{ "Toyota", "Camry" };
35 
36    if (corolla == camry)
37        std::cout << "a Corolla and Camry are the same.\n";
38 
39    if (corolla != camry)
40        std::cout << "a Corolla and Camry are not the same.\n";
41 
42    return 0;
43}
44

1lass Fred {
2public:
3  // ...
4};
5if 
6  // Without operator overloading:
7  Fred add(const Fred& x, const Fred& y);
8  Fred mul(const Fred& x, const Fred& y);
9  Fred f(const Fred& a, const Fred& b, const Fred& c)
10  {
11    return add(add(mul(a,b), mul(b,c)), mul(c,a));    // Yuk...
12  }
13else
14  // With operator overloading:
15  Fred operator+ (const Fred& x, const Fred& y);
16  Fred operator* (const Fred& x, const Fred& y);
17  Fred f(const Fred& a, const Fred& b, const Fred& c)
18  {
19    return a*b + b*c + c*a;
20  }
21#endif