Code Example 1

``````#include <iostream>
using namespace std;

class Box {
public:
double getVolume(void) {
return length * breadth * height;
}
void setLength( double len ) {
length = len;
}
void setBreadth( double bre ) {
}
void setHeight( double hei ) {
height = hei;
}

Box operator+(const Box& b) {
Box box;
box.length = this->length + b.length;
box.height = this->height + b.height;
return box;
}

private:
double length;      // Length of a box
double height;      // Height of a box
};

// Main function for the program
int main() {
Box Box1;                // Declare Box1 of type Box
Box Box2;                // Declare Box2 of type Box
Box Box3;                // Declare Box3 of type Box
double volume = 0.0;     // Store the volume of a box here

// box 1 specification
Box1.setLength(6.0);
Box1.setHeight(5.0);

// box 2 specification
Box2.setLength(12.0);
Box2.setHeight(10.0);

// volume of box 1
volume = Box1.getVolume();
cout << "Volume of Box1 : " << volume <<endl;

// volume of box 2
volume = Box2.getVolume();
cout << "Volume of Box2 : " << volume <<endl;

// Add two object as follows:
Box3 = Box1 + Box2;

// volume of box 3
volume = Box3.getVolume();
cout << "Volume of Box3 : " << volume <<endl;

return 0;
}``````

Code Example 2

``````#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;
}``````

Code Example 3

``````// money.h -- define the prototype
class Money
{
public:
Money & operator += (const Money &rhs);
}

// money.cpp -- define the implementation
Money& Money :: operator += (const Money &rhs)
{