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How to overload pre-increment operator using non-member or free function in C++?

C++ - Overload pre-increment operator using non-member or free function: Here, we will learn to overload operator (pre-increment) using non-member of free function with C++ program.

Prerequisite: operator overloading and its rules

Here, we are going to implement a C++ program that will demonstrate operator overloading (pre-increment) using non-member or free member function.

Note: This type of non-member function will access the private member of class. So the function must be friend type (friend function).

C++ program to overload pre-increment operator using non-member or free function

Consider the program:

using namespace std;
#include <iostream>

// Sample class to demonstrate operator overloading
class Sample {
  // private data members
 private:
  int value;

 public:
  // Parameterized constructor
  Sample(int c) { value = c; }

  // Operator overloading declaration using
  // friend function
  friend Sample operator++(Sample &S);

  // function to print the value
  void printValue() { cout << "Value is : " << value << endl; }
};

// friend function (operator overloading) definition
Sample operator++(Sample &S) {
  ++S.value;
  return S;
}

// main program
int main() {
  int i = 0;
  // object declaration,
  // here parameterized constructor will be called
  Sample S1(100);

  for (i = 0; i < 5; i++) {
    // operator overloading
    ++S1;
    S1.printValue();
  }

  return 0;
}

Output

Value is : 101
Value is : 102
Value is : 103
Value is : 104
Value is : 105