overloading pointers

[Sharan123]

it shows zero value for d3 but it's suppose to add d1 and d2 value to get total in d3

    #include<stdexcept>
#include<conio.h>
#include <iostream>
#include<string.h>
using namespace std;
class Distance
{
private:
double feet ;
double inches;
public:
	Distance():feet(0),inches(0) {}
	Distance(double ft, double inch) : feet (ft ) , inches (inch){}
	void Display()
	{
		cout<<feet<<"-"<<inches<<endl;
	}
	void getDistance()
	{
		cout<<"feet:";
		cin>>feet;
		cout<<endl;
		cout<<"inches:";
		cin>>inches;
	}
	Distance Distance::operator += (Distance d1)
	{
		Distance d2;
		d2.feet =d1.feet+feet;
		d2.inches=d1.inches/12+inches;
		return 
			d2;
		
	}
};
int main () 
{
Distance d1(3,5),d2,d3;
d1.Display();
d2.Display();
d2.getDistance();
d2+=d1;
d3+=d2;
d3.Display();
}

[LB]

Your operator += doesn't modify anything from this, so it does not even change the state of your objects.

[Sharan123]

Thank you why doesn't the operator modify what is the problem in my code

[LB]

Because you create a local variable d2 and modify it, rather than modifying this.

This is what you have (wrong):

	Distance Distance::operator += (Distance d1)
	{
		Distance d2;
		d2.feet =d1.feet+feet;
		d2.inches=d1.inches/12+inches;
		return 
			d2;
		
	}

Try this instead:

	Distance &Distance::operator += (Distance const &other)
	{
		feet += other.feet; //calculation is still wrong
		inches += other.inches/12; //calculation is still wrong
		return *this;
		
	}

Note that your math is still wrong and will not give the correct results, but at least the code is correct.

[Sharan123]

Thank you can you tell me what *this is or refer me an article on it or can't you return a object for it , that would make it less complicated

[o3hC5Di1]

Hi there,

Within an object of a class this is a pointer to that same objects location in memory.
So by doing return *this; you are effectively returning the object in its current state.

Similarly, you could use this within your class to access members:

std::cout << this->feet;

Which can be useful sometimes when dealing with templates.

All the best,
NwN

[Sharan123]

Thank you