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C++ program to overload unary pre-decrement operator and provide support for '=' assignment operator

Overload unary pre-decrement operator and assign the value in another object in C++: Here, we will learn about the operator overloading with an example/program of unary pre-decrement operator in C++? Here, we will assign the decremented value to another object.

Read: operator overloading and its rules

To implement operator overloading, we need to use 'operator' keyword. To assign extra task to operator, we need to implement a function. That will provide facility to write expressions in most natural form.

For example:

S1 is object of class sample then we use like this: S2 = --S1;

C++ program to overload unary pre-decrement operator and provide support for '=' assignment operator

Consider the program:

using namespace std;
#include <iostream>

class Sample {
 private:
  int count;

 public:
  // default constructor
  Sample() { count = 0; }

  // parameterized constructor
  Sample(int c) { count = c; }

  // operator overloading,returnning an object
  Sample operator--() {
    Sample temp;
    temp.count = --count;
    return temp;
  }

  // printing the value
  void printValue() { cout << "Value of count : " << count << endl; }
};

int main() {
  int i = 0;

  // object declarations
  Sample S1(100), S2;

  for (i = 0; i < 5; i++) {
    // calling operator overloading
    // assigning value in other object
    S2 = --S1;

    cout << "S1 :" << endl;
    S1.printValue();

    cout << "S2 :" << endl;
    S2.printValue();
  }

  return 0;
}

Output

S1 :
Value of count : 99
S2 :
Value of count : 99
S1 :
Value of count : 98
S2 :
Value of count : 98
S1 :
Value of count : 97
S2 :
Value of count : 97
S1 :
Value of count : 96
S2 :
Value of count : 96
S1 :
Value of count : 95
S2 :
Value of count : 95

Explanation

In this program, we have created a class named Sample. It contains a data member value. And we have implemented a function to overload pre-decrement operator with support of = assignment operator.

We cannot use post- decrement with this method of operator overloading.

We can use below statement also in place of S2 = --S1: S2 = S1.operator--();