operator overloading

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

// money.cpp -- define the implementation
Money& Money :: operator += (const Money &rhs)
{
   // Yadda Yadda
  
   return *this;
}

#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;
}

#include <iostream>
using namespace std;

class Test
{
   private:
      int count;

   public:
       Test(): count(5){}

       void operator ++() 
       { 
          count = count+1; 
       }
       void Display() { cout<<"Count: "<<count; }
};

int main()
{
    Test t;
    // this calls "function void operator ++()" function
    ++t;    
    t.Display();
    return 0;
}

#include<iostream> 
using namespace std; 
  
class Complex { 
private: 
    int real, imag; 
public: 
    Complex(int r = 0, int i =0)  {real = r;   imag = i;} 
      
    // This is automatically called when '+' is used with 
    // between two Complex objects 
    Complex operator + (Complex const &obj) { 
         Complex res; 
         res.real = real + obj.real; 
         res.imag = imag + obj.imag; 
         return res; 
    } 
    void print() { cout << real << " + i" << imag << endl; } 
}; 
  
int main() 
{ 
    Complex c1(10, 5), c2(2, 4); 
    Complex c3 = c1 + c2; // An example call to "operator+" 
    c3.print(); 
} 

#include<iostream> 
using namespace std; 
  
class Complex { 
private: 
    int real, imag; 
public: 
    Complex(int r = 0, int i =0)  {real = r;   imag = i;} 
    void print() { cout << real << " + i" << imag << endl; } 
  
// The global operator function is made friend of this class so 
// that it can access private members 
friend Complex operator + (Complex const &, Complex const &); 
}; 
  
  
Complex operator + (Complex const &c1, Complex const &c2) 
{ 
     return Complex(c1.real + c2.real, c1.imag + c2.imag); 
} 
  
  
int main() 
{ 
    Complex c1(10, 5), c2(2, 4); 
    Complex c3 = c1 + c2; // An example call to "operator+" 
    c3.print(); 
    return 0; 
}