C++: Variable not initialized within "while" loop

Quick backstory: I am a college student taking C++ for an engineering major. I have never done any programming at all so my problems will be a touch elementary. I apologize in advance for my ignorance and greatly appreciate all the help I can get.

Now to my problem.

I have to write a simple program to calculate the volume of cylinders while drawing the numbers needed from a file. When I build the program, it builds successfully. However, when I run my program, it tells me my variable "h" is not initialized.

Code:

int main()
{
	cout << "Zachary Jones" << endl;
	cout << "Project 3" << endl;
	cout << "Febuary 23, 2011" << endl;

	const float PI = 3.141592;
	float volume2, h, r, i, V, c;   // h = height, r = radius, i = increase %, v = volume, c = radius of new cylinder

	char filename[100] = "cylinderdata.txt";
	
	// Create File
	ifstream cylinderdata;
	cylinderdata.open(filename);

	

	//Volume Program and loop
	while (h > -999)
	{
		// Read in data
	cylinderdata >> h >> r >> i ;

		V = PI * pow(r,2) * h;
		cout << "Volume of Cylinder is " << V <<endl <<endl;
		volume2 = ((i/100) + 1) * V;
		c = sqrt((volume2)/(PI*h));
		cout << "The radius of the new cylinder is " << c << endl << endl;

	}

	return 0;
}

I want to think it has something to do with the source file for the numbers but as best I can tell, it's right where it needs to be.

Any help or suggestions?

float volume2, h,

It's fine where you put it but it is not initialised no, initialise means 'assign a value to' (In general terms when talking about variables anyway)

It is always a good idea to set a zero for example to any number variables. When they are created, sometimes it is obvious that the value will immediately be initialised anyway, like in a FOR loop, but it is a good habit to get into nontheless, Especially in cases like this, your while loop needs to be sure what ' h ' is before it starts executing, otherwise how can it work correctly? In your case 'h' will just have some wild value assigned that canot be predicted.

Basically, the first time through the loop, h doesn't have a value yet.

Some things to consider:
1) Any input error (such as the user accidentally inputting text) will cause this program to loop forever, wildly writing out data. You might want to learn about validating input.
2) Instead of writing
float h; // h = height
why not write
float height;
?
You have lots and lots of one-letter variables and comments explaining what they mean. It would be much better if your variable names explained what they mean by themselves. Modern IDEs even save you from having to type the long names.