Question

This is a question from a past exam paper. The code was given in the question and i need to gain the values and how many times the breakpoint is it. I have tried running the code in eclipse but to no avail. (I could find the values in debug mode if code executed)

Also the question states that: the method fact is called on an instance of the class in which n has the value 6. Not sure what I am doing wrong as the code is exactly the same as given in the question.

public class FactLoop {

private int n;// assumed to be greater than or equal to 0

/**
 * Calculate factorial of n
 * 
 * @return n!
 */
public int fact() {
    int i = 0;
    int f = 1;

    /**
     * loop invariant 0<=i<=n and f=i!
     */

    while (i < n) {// loop test (breakpoint on this line)
        i = i++;
        f = f * i;
    }
    return f;
}

// this main method is not a part of the given question
public static void main(String[] args) {
    FactLoop fl = new FactLoop();
    fl.n = 6;
    System.out.println(fl.fact());
}

}

Answer 1

Your error is in i=i++;. i++ increments i, and retuns i’s old value. By saying i=i++, you increment it, then set it to its old value.

Just use i++; to increment it.