Multiple choice technology programming languages

What is the output of following Program class C{ static int f1(int i) { System.out.print(i + ","); return 0; } public static void main (String[] args) { int i = 0; i = i++ + f1(i); System.out.print(i); } }

  1. Prints: 0,0

  2. Prints: 1,0

  3. Prints: 0,1

  4. Compile-time error

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In i = i++ + f1(i), the post-increment operator i++ returns the current value (0) then increments i to 1. So f1 receives 0, prints '0,', and returns 0. The expression becomes i = 0 + 0 = 0, but wait - after i++ executes, i becomes 1. So the right side evaluates to 0+0=0, then i (which is 1 from the increment) is assigned 0. Actually, let me trace more carefully: i starts at 0. i++ returns 0, then i becomes 1. f1(i) where i=1 now is called... but the parameter is evaluated before the increment? No, parameters are evaluated left to right. So f1 receives 0, prints '0,'. The expression is 0 + 0 = 0. i is set to 0. But the post-increment made i=1 temporarily, but then the assignment overwrites it. Output: '0,0'. Wait, option B says '1,0'. Let me reconsider. Actually Java evaluates i++ first (returns 0, i becomes 1), then evaluates f1(i) - but what's i at this point? It's 1. So f1(1) prints '1,' and returns 0. Then 0+0=0. Output: '1,0'.

AI explanation

Java evaluates 'i++ + f1(i)' left to right. First, i++ reads the current value of i (0) for use in the addition, then immediately increments i to 1 as a side effect (this happens before the second operand is evaluated). Next, f1(i) is called with the now-updated i=1, printing '1,' and returning 0. So the sum is 0 (from i++) + 0 (from f1) = 0, which is then assigned back to i, overwriting the 1 with 0. The final print(i) therefore prints '0'. Combined with f1's earlier print, the full output is '1,0', matching the marked answer — a good illustration of Java's strict left-to-right evaluation order combined with post-increment's 'read-then-increment' semantics.