/**
 * This program reads a positive integer from the user.
 * It counts how many divisors that number has, and
 * then it prints the result.
 * 
 * (Note: This program works for any integer in the range
 * 1 to 2147483646, but it crashes with a division-by-zero
 * when run with input 2147483647, the largest value of type
 * int.  This happens because 2147483647 + 1 is -2147483648,
 * the smallest value of type int.   So, after processing
 * testDivisor = 2147483647, testDivisor becomes -2147483648,
 * and the loop continues.  Eventually, testDivisor will be 
 * zero, and the expression  N % testDivisor is trying to
 * divide N by zero.)
 */

public class CountDivisors {

    public static void main(String[] args) {

        int N;  // A positive integer entered by the user.
                // Divisors of this number will be counted.

        int testDivisor;  // A number between 1 and N that is a
                          // possible divisor of N.

        int divisorCount;  // Number of divisors of N that have been found.

        int numberTested;  // Used to count how many possible divisors
                           // of N have been tested.  When the number
                           // reaches 1000000, a period is output and
                           // the value of numberTested is reset to zero.

        /* Get a positive integer from the user. */

        while (true) {
            System.out.print("Enter a positive integer: ");
            N = TextIO.getlnInt();
            if (N > 0)
                break;
            System.out.println("That number is not positive.  Please try again.");
        }

        /* Count the divisors, printing a "." after every 1000000 tests. */

        divisorCount = 0;
        numberTested = 0;

        for (testDivisor = 1; testDivisor <= N; testDivisor++) {
            if ( N % testDivisor == 0 )
                divisorCount++;
            numberTested++;
            if (numberTested == 1000000) {
                System.out.print('.');
                numberTested = 0;
            }
        }

        /* Display the result. */

        System.out.println();
        System.out.println("The number of divisors of " + N
                + " is " + divisorCount);

    } // end main()

} // end class CountDivisors