Code for pi-cannon example.
Single main file.
Compile as a Symantec C++ with iostreams project or Borland EasyWin project.
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#include <stdlib.h>
#include <iostream.h>
#include <math.h>


long GetAmmunition(void)
{
	long	munition;
	long	seed;
	cout << "Please Professor, how many shots should we fire?";
	// Read shots, maybe we should use that GetIntegerInRange
	// to make certain that the prof enters a sensible value
	// Risk it, hope he can type a number
	cin >> munition;
	// Need seed for random number generator,
	// Get prof to enter it (that way he has chance of
	// getting same results twice).  Don't confuse him
	// with random number stuff, just get a number.
	cout << "Please Professor, which gunner should lay the gun?"
			<< endl;
	cout << "Please enter a gunner identifier number 1..1000 :";
	cin >> seed;
	srand(seed);
	return munition;
}

int TestInCircle(double x, double y)
{
	// Use the sqrt() function from math.h 
	// rather than NewtRoot()!
	// Remember to #include <math.h>
	double distance = sqrt(x*x + y*y);
	return distance < 100.0;
}

double PiEstimate(long squareshot, long circleshot)
{
	return 4.0*double(circleshot)/squareshot;
}


double GetCoordinate(void)
{
	int	n = rand();
	// Take n modulo 201, i.e. remainder on dividing by 201
	// That should be a number in range 0 to 200
	// deduct 100
	n = n % 201;
	return double(n-100);
}


void	PrintPIEstimate(double pi, long shotsused)
{
	cout << "Estimate for pi, based on results of"
	  << shotsused << " shots, is " << pi << endl;
}

int main()
{
	long	fired = 0, ontarget = 0, ammunition;
	double	pi = 4.0; // Use the colonel's estimate!
	long	freq, count;
	
	ammunition = GetAmmunition();

	freq = ammunition / 10;
	count = 0;

	for(; ammunition > 0; ammunition--) {
		double x, y;
		fired++;
		x = GetCoordinate();
		y = GetCoordinate();
		if(TestInCircle(x, y))
			ontarget++;
		
		count++;
		if(count == freq) {
			// Time for another estimate
			pi = PiEstimate(fired, ontarget);
			PrintPIEstimate(pi, fired);
			// reset count to start over
			count = 0;
			}
		}

	cout << "We've used all the ammunition." << endl;
	cout << "Our final result:" << endl;
	pi = PiEstimate(fired, ontarget);
	PrintPIEstimate(pi, fired);
	return 0;
}