how to apply operator overloading for unary postfix operator

Question

below is code for operator overloading for unary operator ++

#include <iostream>
using namespace std;
 
class Distance {
   private:
      int feet;             // 0 to infinite
      int inches;           // 0 to 12
      
   public:
      // required constructors
      Distance() {
         feet = 0;
         inches = 0;
      }
      Distance(int f, int i) {
         feet = f;
         inches = i;
      }
      
      // method to display distance
      void displayDistance() {
         cout << "F: " << feet << " I:" << inches <<endl;
      }
      
      // overloaded minus (-) operator
      Distance operator++ () {
         feet = feet+1;
         inches = inches+1;
         
         return Distance(feet, inches);
      }
};

int main() {
   Distance D1(11, 10), D2(-5, 11);
 
   ++D1;                     // increment by 1
   
   D1.displayDistance();    // display D1

   ++D2;                     // increment by 1
   D2.displayDistance();    // display D2

   return 0;
}

when I use above code then I can successfully use prefix operator ++D1 and ++D2 but I am not getting how to overload postfix operator D1++ and D2++ even if I try these in above code it showing me error so how can we use concept of operator overloading for postfix and prefix separately?

Answer 1

if you want post-inc/dec then the code will be :

  Distance operator++ (int) {
     feet = feet+1;
     inches = inches+1;
     
     return Distance(feet, inches);
  }

we use int in formal parameter . it is just crate different between post/pre-fix. The prefix form of the operator is declared exactly the same way as any other unary operator; the postfix form accepts an extra argument of type int.