Given: ``java public class Calculator { public static void main(String[] args) { int num = 5; int sum; do { sum += num; } while ( (num--) > 1); System.out.println("The sum is " + sum + "."); } } ``…

Question

public class Calculator {
 public static void main(String[] args) {
 int num = 5;
 int sum;
 do {
 sum += num;
 } while ( (num--) > 1);
 System.out.println("The sum is " + sum + ".");
 }
}

Options

• AThe sum is 2
• BThe sum is 14
• CThe sum is 15
• DThe loop executes infinite times
• ECompilation fails

• B
  5% (1)
• C
  5% (1)
• D
  11% (2)
• E
  79% (15)

Explanation

Compilation fails because sum is declared as a local variable (int sum;) but never initialized before being read in sum += num. In Java, unlike instance fields (which default to 0), local variables have no default value - the compiler enforces explicit initialization and will throw a "variable sum might not have been initialized" compile-time error before the program can run.

Options A, B, C, and D are all runtime-level answers that assume the code compiles, which it never does. If sum were correctly initialized to 0, the do-while loop would add 5+4+3+2+1 = 15 (C), because the post-decrement num-- checks the current value before decrementing, so the body still runs when num=1 (where 1 > 1 is false and the loop exits after that iteration). B (14) is the off-by-one trap for misreading post-decrement, and D (infinite loop) is wrong because num steadily decreases until the condition fails.

Memory tip: Think "local = lonely" - local variables get no automatic initialization; they must be explicitly assigned before use, or the compiler refuses to proceed.

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