Answer to Question #327675 in C++ for Mominul

Question

Explain how overloading a unary operator is almost similar to overloading a binary operator with necessary examples and include main() function to demonstrate. Mention the differences between these two in terms of number of operands they deal with.

Answer 1

Hello! In general, both the overloading a unary operator and overloading a binary operator have similar signature:

(data type) operator(symbol of operator) (input parameters)
{
	//some code here 
}

For example: 

class Point
{
public:
	int x;
	int y;
	
	Point(int x_, int y_) :x(x_), y(y_) {}
	Point operator+(Point second_number) // operator+ receives two arguments: this and second_number
	{
		return Point(this->x * second_number.x, this->y * second_number.y);
	}
};

This function overload a binary operator “+” and returns the object of Point with x = the product of the this->x and the second_num.x and y = the product of the this->.y and the second_num.y.

int main() {
	Point a(1, 2);
	Point c = c + a; // it's equals to c.operator+(a); 
	
    return 0;
}

But this is not a good example of overloading. It makes our code more incomprehensible, because user don’t expect that operator + will work like a multiplication We only use the overloading operators when it will make code easier and understandable. For example, we can overload operator + to calculating vector’s sum. (Because user will expect this) 

 

The main difference between overloading a unary operator and overloading a binary operator is the number of input arguments. Overloading a binary operator requires two arguments, while overloading a unary one only one argument. 

	Point operator!() //only one argument - this
	{
		return Point(-this->x, -this->y);
	}

Unary operators: ++, --, !, ~, [], *, &, () 

Binary operators: +, -, *, /, %, ==, !=, >, <, >=, <=, &&, ||, &, |, ^, <<, >>, +=, -=, *=, /=, %=, &=, |=, ^=, <<=, >>=, ->, ->*, (,), ","