operator overload and operator overriding in c++ code example

Example 1: Explain operator overloading with an example.

In C++, we can change the way operators work for user-defined types like objects and structures. This is known as operator overloading. For example,

Suppose we have created three objects c1, c2 and result from a class named Complex that represents complex numbers.

Since operator overloading allows us to change how operators work, we can redefine how the + operator works and use it to add the complex numbers of c1 and c2 by writing the following code:

result = c1 + c2;
instead of something like

result = c1.addNumbers(c2);
This makes our code intuitive and easy to understand.

Note: We cannot use operator overloading for fundamental data types like int, float, char and so on.

Syntax for C++ Operator Overloading
To overload an operator, we use a special operator function.

class className {
    ... .. ...
    public
       returnType operator symbol (arguments) {
           ... .. ...
       } 
    ... .. ...
};

Example 2: c++ overloaded == operator

#include <iostream>
#include <string>
 
class Car
{
private:
    std::string m_make;
    std::string m_model;
 
public:
    Car(const std::string& make, const std::string& model)
        : m_make{ make }, m_model{ model }
    {
    }
 
    friend bool operator== (const Car &c1, const Car &c2);
    friend bool operator!= (const Car &c1, const Car &c2);
};
 
bool operator== (const Car &c1, const Car &c2)
{
    return (c1.m_make== c2.m_make &&
            c1.m_model== c2.m_model);
}
 
bool operator!= (const Car &c1, const Car &c2)
{
    return !(c1== c2);
}
 
int main()
{
    Car corolla{ "Toyota", "Corolla" };
    Car camry{ "Toyota", "Camry" };
 
    if (corolla == camry)
        std::cout << "a Corolla and Camry are the same.\n";
 
    if (corolla != camry)
        std::cout << "a Corolla and Camry are not the same.\n";
 
    return 0;
}