Variable scope and lifetime: Correct Solution

Given the following code:

public class CemWedmal {
    private int cic = 0;

    public void ounbot(int ta) {
        int baen = 0;
        cic += ta;
        baen += ta;
        eph += ta;
        System.out.println("cic=" + cic + "  baen=" + baen + "  eph=" + eph);
        A
    }

    private static int eph = 0;

    public static void main(String[] args) {
        B
        CemWedmal c0 = new CemWedmal();
        CemWedmal c1 = new CemWedmal();
        C
        c0.ounbot(1);
        c0 = new CemWedmal();
        c1.ounbot(10);
        c0.ounbot(100);
        c1 = c0;
        c1.ounbot(1000);
    }
}
  1. What does the main method print?
  2. Which of the variables [eph, cic, baen, c0, c1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    eph=1  cic=1  baen=1
eph=10  cic=10  baen=11
eph=100  cic=100  baen=111
eph=1100  cic=1000  baen=1111

  2. In scope at A : baen, eph

  3. In scope at B : baen, c0

  4. In scope at C : baen, c0, c1

Explanation (which you do not need to write out in your submitted solution):

  1. baen is a static variable, eph is an instance variable, and cic is a local variable.

  2. At A , cic is out of scope because it is not declared yet. c0 and c1 out of scope because they are local to the main method.

  3. At B , c1 is out of scope because it is not declared yet. eph is out of scope because it is an instance variable, but main is a static method. cic is out of scope because it is local to ounbot.

  4. At C , eph is out of scope because it is an instance variable, but main is a static method. cic is out of scope because it is local to ounbot.

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