Code used in my first medium article. Check it out here https://medium.com/@rudra.desai200/how-to-use-const-keyword-in-c-b65ee42cf09

medium1snip1.cpp

class Dummy {
 	private:
 		int X = 0;
	 public:
		//this function will give an error if 
		//object declared is of constant type
		int getX() { return X; }

		//this function will work fine as
		//we have declared it const. 
		void printX() const { std::cout<<X<<std::endl; }
};

int main(){
	 const Dummy d;
	 // d.getX(); //it will return a compilation error if uncommented
	 d.printX(); //it will work just fine
}