// Source: "Software Design ...", John A Robinson, Newnes, 2004, page 67.
//
// Division tester program
//
#include <iostream>
#include <cstdlib>              // For random number functions
#include <ctime>                // For time functions
using namespace std;

int main()
	{
	int dividend, divisor, answer;   // answer = dividend/divisor
	int users_answer;
	long start_time;       	// long because return value from time() is long
	int duration;
	int sum_correct = 0;
	int sum_durations = 0;
	int i;         		// Counter
	srand(time(NULL));  	// Use the current time to "seed" the random number
			    	// generator
	for (i = 0; i < 10; i++)
		{
		answer = rand()/(RAND_MAX/8) + 2;  // Generate answer and divisor, then work out
		divisor = rand()/(RAND_MAX/8) + 2; // dividend from them. See text for explanation
		dividend = answer*divisor;         // of random number generation.
		cout << "What is " << dividend << " divided by " << divisor << "?\n";
		start_time = time(NULL);
		cin >> users_answer;
		if (users_answer != answer)
			cout << "Wrong! The answer is " << answer << '\n';
		else
			{
			cout << "Right! (in " << (duration = time(NULL)-start_time) << " seconds)\n";
			sum_correct++;
			sum_durations += duration;
			}
		}
	cout << sum_correct << " out of 10 correct.\n";
	if (sum_correct)
		cout << "Average time =  " << (double) sum_durations/sum_correct << " seconds\n";
	return 0;
	}