Why Wont My Functions Process The New Values?

[DavidGambino]

Hi all,

So I was given an assignment where I have to input two points (four integers) on a Cartesian plane from a file and then process it using functions. My professor is very particular so the comments are a bit excessive, but here's what I have.

  double radiusFn(double, double, double, double);	//4 double values, one for each point. All points are needed for the calculation of distance in this function.
double diameterFn(double);							//Only uses one double value - the radius. Both functions below use the same value.
double circumferenceFn(double);
double areaFn(double);

int main()
{
	cout << "---------------------------------------------------------" << endl;
	cout << "               Circle Statistics Program" << endl;
	cout << "                    David Gambino" << endl;
	cout << "---------------------------------------------------------" << endl;


	ifstream fin;
	fin.open("assignment3data.txt");

	while (fin)
	{

		int x1, x2, y1, y2;
		fin >> x1 >> y1 >> x2 >> y2;
		double radius = sqrt(pow((x2 - x1), 2) + pow((y2 - y1), 2));		//Distance formula.
		double points, diameter, circumference, area;

		if (fin)
		{	


			diameter = diameterFn(radius);				//Variable diameter is assigned the value outputted by diameterFn using the value of radius which was just determined.
			circumference = circumferenceFn(radius);	//Variable circumference is assigned the value outputted by circumferenceFn using the value of radius.
			area = areaFn(radius);						//Variable area is assigned the value outputted by areaFn using the value of radius.

			cout << "Statistics for points (" << x1 << ',' << y1 << ") and  (" << x2 << ',' << y2 << ')' << endl;			//implementations proceeding function main.
			cout << fixed << "The radius is: " << setprecision(2) << radius << endl;
			cout << "The diameter is: " << diameter << endl;
			cout << "The circumference is: " << circumference << endl;
			cout << "The area is: " << area << endl << endl;
		}
	}

	fin.close();
}


double diameterFn(double radius)		//Implements calculations to find the diameter of the circle which is simply the radius multiplied by 2.
{
	double diameter = radius * 2;		//Diameter formula.
	return diameter;
}
double circumferenceFn(double radius)				//Implements calculations to find the circumference of the circle.
{
	double circumference = 2 * 3.1416*radius;		//Circumference formula. 3.1416 is pi to the forth decimal place.
	return circumference;
}
double areaFn(double radius)					//Implements calculations to find the circumference of the circle.
{
	double area = 3.1416*pow(radius, 2);		//Area formula.
	return area;
}

The file reads:

1 2 3 4 5 6 7 8 9 10 11 12

It compiles fine, but after the first loop the functions keep return identical statistics, although the outputted values for the x's and y's when I execute the program are changing.

Can anyone tell me how to fix this?
Thanks in advance!

[48T7M4Gy]

line 17 should be while (!fin.eof())

line 25 should be deleted

Note that while/if (fin) is always true, which is not what you mean I guess.

[PCrumley48]

With the input numbers you have, it will always return the same values:

First set of numbers:

x1 = 1, y1 = 2, x2 = 3, y2 = 4

Therefore, in line 22:

radius = sqrt(pow((x2 - x1), 2) + pow((y2 - y1), 2))

same as

radius sqrt(pow((3-1),2) + pow((4 - 2),2);
radius = sqrt(pow((2),2) + pow((2),2)

second set of numbers:

x1 = 5, y1 = 6, x2= 7, y2=8

In line 22:

radius = sqrt(pow((7 - 5),2) + pow((8 - 6),2));
radius = sqrt(pow((2),2) + pow((2),2)

Not a problem, right? Any four sequential numbers will give identical results.

[48T7M4Gy]

That's a good point about the sequential data. So use something like the following data. Make the program changes. And you'll get some sensible output as follows the data set. ( I haven't checked the arithmetic.

11
2
8
-1
7
6
5
77
9
10
-54
12

---------------------------------------------------------
               Circle Statistics Program
                    David Gambino
---------------------------------------------------------
Statistics for points (11,2) and  (8,-1)
The radius is: 4.24
The diameter is: 8.49
The circumference is: 26.66
The area is: 56.55

Statistics for points (7,6) and  (5,77)
The radius is: 71.03
The diameter is: 142.06
The circumference is: 446.28
The area is: 15849.37

Statistics for points (9,10) and  (-54,12)
The radius is: 63.03
The diameter is: 126.06
The circumference is: 396.04
The area is: 12481.58