C++ program to overload unary pre-decrement operator

Overload unary pre-decrement operator in C++: Here, we will learn about the operator overloading with an example/program of unary pre-decrement operator in C++?

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.

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;}      

		//overloaded operator 
		void operator--()
		{ --count;}

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

int main()
{
	int i = 0;
	
	//object delaration
	Sample S1(100);

	for(i=0; i< 10; i++)
	{    
		//operator overloading will be applied
		--S1;
		//S1--; //Error
		S1.printValue();
	}

	return 0;    
}

Output

Value of count : 99
Value of count : 98
Value of count : 97
Value of count : 96
Value of count : 95
Value of count : 94
Value of count : 93
Value of count : 92
Value of count : 91
Value of count : 90

In this program, there is a class named Sample and it contains a data member value and we have implemented a function to overload pre-decrement operator.

--S1 (Unary pre-decrement overloaded operator) will decrease the value of data member value.

But, we cannot use post-decrement with this method of operator overloading.