Testing and Debugging

Timing Probe

A deterministic counter can stand in for timing work when teaching how to compare paths.

Timing Probe

TimingProbe.java 
public class TimingProbe {
    public static void main(String[] args) {
        int limit = ;
        int slowSteps = 0;
        int fastSteps = 0;

        for (int i = 0; i < limit; i++) {
            slowSteps++;
        }

        for (int i = 0; i < limit; i += 2) {
            fastSteps++;
        }

        System.out.println("slow=" + slowSteps + " fast=" + fastSteps);
    }
}

public class TimingProbe {
    public static void main(String[] args) {
        int limit = ;
        int slowSteps = 0;
        int fastSteps = 0;

        for (int i = 0; i < limit; i++) {
            slowSteps++;
        }

        for (int i = 0; i < limit; i += 2) {
            fastSteps++;
        }

        System.out.println("slow=" + slowSteps + " fast=" + fastSteps);
    }
}

public class TimingProbe {
    public static void main(String[] args) {
        int limit = ;
        int slowSteps = 0;
        int fastSteps = 0;

        for (int i = 0; i < limit; i++) {
            slowSteps++;
        }

        for (int i = 0; i < limit; i += 2) {
            fastSteps++;
        }

        System.out.println("slow=" + slowSteps + " fast=" + fastSteps);
    }
}
probe counter A counter records how many loop steps were needed without relying on wall-clock time.
comparable paths The two loops do the same kind of work, so their counts can be compared directly.