Simple program giving solution of -0?

[yosimba2000]

Why is the program giving me a solution of -0? The program is simulating the slope formula between two points. I never had a problem like this in Java.

Here is my code:



#include <iostream>
using namespace std;
int main()
{
double x,y,xs,ys;
double slope = (ys-y)/(xs-x);
cout<<"Please input your first X coordinate with at least one trailing decimal place. \n\n";
cin>> x;
cout<<"Please input your first Y coordinate with at least one trailing decimal place. \n\n";
cin>>y;
cout<<"Please input your second X coordinate with at least one trailing decimal place. \n";
cin>>xs;
cout<<"Please input your second Y coordinate with at least one trailing decimal place. \n";
cin>>ys;
cin.get();

cout<<"Your resulting slope from the line connecting these two points is " <<slope<< ".\n";
cin.get();
return 0;
}

[vlad from moscow]

You did not initialize variables

double x,y,xs,ys;

So they have arbitrary values and as the result value of double slope = (ys-y)/(xs-x);
can be also arbitrary. So behavior of your program is undefined.

[gfleece]

In other words, "slope" is trying to do math on undefined variables. They are not defined until after the math is done. Put the "double slope = ....." after cin.get(); before "Your resulting....." That should make it work.

#include <iostream>
using namespace std;
int main()
{
	double x,y,xs,ys;
	double slope;

	cout<<"Please input your first X coordinate with at least one trailing decimal place. \n\n";
	cin>> x;
	cout<<"Please input your first Y coordinate with at least one trailing decimal place. \n\n";
	cin>>y;
	cout<<"Please input your second X coordinate with at least one trailing decimal place. \n";
	cin>>xs;
	cout<<"Please input your second Y coordinate with at least one trailing decimal place. \n";
	cin>>ys;
	cin.get();

	slope = (ys-y)/(xs-x);

	cout<<"Your resulting slope from the line connecting these two points is " <<slope<< ".\n";
	cin.get();
	return 0;
}

[cire]

In other words, "slope" is trying to do math on undefined variables. They are not defined until after the math is done. Put the "double slope = ....." after cin.get(); before "Your resulting....." That should make it work.

If the variables were undefined, it wouldn't compile. As Vlad said, they were uninitialized.

[yosimba2000]

program is working fine now, thanks guys.