C++ LANGUAGE INCREMENT(++) AND DECREMENT(--) OPERATORS

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C++ LANGUAGE INCREMENT(++) AND DECREMENT(--) OPERATORS

Increment (++) and Decrement (- -) Operators 


The increment (++) and decrement (--) operators are two 
important unary operators available in C++. 
Following example explain how increment (++) operator 
can be overloaded for prefix as well as postfix usage. 
Similar way, you can overload operator (--). 

#include <iostream> 

using namespace std; 
  
class Time 
{ 
   private: 
      int hours;             // 0 to 23 
      int minutes;           // 0 to 59 
   public: 
      // required constructors 
      Time(){ 
         hours = 0; 
         minutes = 0; 
      } 
      Time(int h, int m){ 
         hours = h; 
         minutes = m; 
      } 
      // method to display time 
      void displayTime() 
      { 
         cout << "H: " << hours << " M:" << minutes <<endl; 
      } 
      // overloaded prefix ++ operator 
      Time operator++ ()   
      { 
         ++minutes;          // increment this object 
         if(minutes >= 60)   
         { 
            ++hours; 
            minutes -= 60; 
         } 
         return Time(hours, minutes); 
      } 
      // overloaded postfix ++ operator 
      Time operator++( int )          
      { 
         // save the orignal value 
         Time T(hours, minutes); 
         // increment this object 
         ++minutes;                     
         if(minutes >= 60) 
         { 
            ++hours; 
            minutes -= 60; 
         } 
         // return old original value 
         return T;  
      } 
}; 


int main() 
{ 
   Time T1(11, 59), T2(10,40); 
  
   ++T1;                    // increment T1 
   T1.displayTime();        // display T1 
   ++T1;                    // increment T1 again 
   T1.displayTime();        // display T1 
  
   T2++;                    // increment T2 
   T2.displayTime();        // display T2 
   T2++;                    // increment T2 again 
   T2.displayTime();        // display T2 
   return 0; 
} 


When the above code is compiled and executed, it produces the following result: 
H: 12 M:0 
H: 12 M:1 
H: 10 M:41 
H: 10 M:42