C++ Binary Operator Overloading Greater or Less than

In a previous c++ language tutorial we looked at C++ overloading of binary operators. In the comment section of this tutorial the user ‘prince’ asked for a binary operator overloading example of greater than. This tutorial is the answer to his question.

Unary or Binary Operator

First let’s find out if the greater than (>) and less than (<) operators are of the type unary or binary operators.
If you look-up the in the unary and binary operator table you’ll see that the two operators are of the type binary operators.

Overloading greater than And less than Operators

The binary operators greater than (>) and less than (<) operators are mostly used in if statements, so the source code example below is also using if statements. Let’s look at the operator overloading source code:

#include<iostream>
using namespace std;

class Box {
	public:
		Box(double boxLength, double boxWidth, double boxHeight)
			:length(boxLength), width(boxWidth), height(boxHeight) {}
		
		// Compute the volume of a box.
		double volume() const {
			return length*width*height;
		}
		
		// First inline function
		inline bool operator<(const Box& someBox) const {
			return volume() < someBox.volume();
		}
		
		// Second inline function
		inline bool operator<(const double someValue) const {
			return volume() < someValue;
		}
		
		// Third inline function
		inline bool operator>(const Box& someBox) const {
			return volume() > someBox.volume();
		}
		
		// Fourth inline function
		inline bool operator>(const double someValue) const {
			return volume() > someValue;
		}
	
	private:
		double length;
		double width;
		double height;
};


int main() {
	Box myBox(15.0, 10.0, 5.0);
	Box myBox2(15.0, 5.0, 5.0);
	
	cout << "The myBox volume is: " << myBox.volume() << "\n";
	cout << "The myBox2 volume is: " << myBox2.volume() << "\n";

	// Trying the less than binary operator
	if(myBox < myBox2) {
		cout << "The myBox volume is less than myBox2 volume!\n";
	}else{
		cout << "The myBox volume is not less than myBox2 volume!\n";
	}
	
	// Trying the less than binary operator
	if(myBox < 1000) {
		cout << "The myBox volume is less than 1000!\n";
	}else{
		cout << "The myBox volume is not less than 1000!\n";
	}
	
	// Trying the greater than binary operator
	if(myBox > myBox2) {
		cout << "The myBox volume is greater than myBox2 volume!\n";
	}else{
		cout << "The myBox volume is not greater than myBox2 volume!\n";
	}
	
	// Trying the greater than binary operator
	if(myBox > 500) {
		cout << "The myBox volume is greater than 500!\n";
	}else{
		cout << "The myBox volume is not greater than 500!\n";
	}
	
	return 0;
}

First we declare two boxes (myBox and myBox2) of the type box, each with a specific volume. Then we use the volume function from the Box class to compute the volume of each box and print the volume size on the screen.

The first if statement is using the first inline function of the Box class. The less than operator is used to ask the question if myBox volume is smaller than myBox2 volume.

The second if statement in main is using the second inline function of the Box class. The less than operator is used to ask the question if myBox volume is smaller than 1000.

The third if statement is using the third inline function of the Box class. The greater than operator is used to ask the question if myBox volume is larger than myBox2 volume.

The fourth if statement in main is using the fourth inline function of the Box class. The greater than operator is used to ask the question if myBox volume is larger than 500.

These are just four easy examples of binary operator overloading of (greater than). We hope that this answer the users comment question and that the rest of the users find it also helpful.

That’s all for this tutorial.