Variable scope and lifetime: Correct Solution

Given the following code:

public class Eiph {
    private static int e = 0;

    public void fenrar(int en) {
        A
        int terd = 0;
        terd += en;
        e += en;
        sa += en;
        System.out.println("terd=" + terd + "  e=" + e + "  sa=" + sa);
    }

    private int sa = 0;

    public static void main(String[] args) {
        Eiph e0 = new Eiph();
        B
        Eiph e1 = new Eiph();
        e0.fenrar(1);
        e1.fenrar(10);
        e0.fenrar(100);
        e1 = new Eiph();
        e0 = e1;
        e1.fenrar(1000);
        C
    }
}
  1. What does the main method print?
  2. Which of the variables [sa, terd, e, e0, e1] are in scope at A ?
  3. Which are in scope at B ?
  4. Which are in scope at C ?

Solution

  1. Output:

    sa=1  terd=1  e=1
sa=10  terd=11  e=10
sa=100  terd=111  e=101
sa=1000  terd=1111  e=1000

  2. In scope at A : terd, e, sa

  3. In scope at B : terd, e0, e1

  4. In scope at C : terd

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

  1. terd is a static variable, e is an instance variable, and sa is a local variable.

  2. At A , e0 and e1 out of scope because they are local to the main method.

  3. At B , e is out of scope because it is an instance variable, but main is a static method. sa is out of scope because it is local to fenrar.

  4. At C , e0 and e1 are out of scope because they are not declared yet. e is out of scope because it is an instance variable, but main is a static method. sa is out of scope because it is local to fenrar.

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