GATE 2026 CS1 Q.63: solution and answer

GATE 2026 · CS1Q.63 · 2 marks · NAT

Consider the following program snippet. Assume that the program compiles and runs successfully. Further, assume that the fork() system call is always successful in creating a process.

int main () {
    int i;
    for (i = 0; i < 3; i++){
        if (fork() == 0){
            continue;
        }
        break;
    }
    printf("Hello!");
    return 0;
}

The total number of times that the printf statement gets executed is ________. (answer in integer)

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Answer and solution

ANSWER

The printf statement is executed 4 times.

Official answer: 4Source: Official answer key, GATE 2026 CS1 (IIT Guwahati)

fork() returns 0 in the child and a positive PID in the parent. The child runs continue and moves to the next iteration. The parent skips the if body, runs break, leaves the loop and reaches printf.
Iteration $i = 0$ : the original process $P_{0}$ forks $P_{1}$ . $P_{0}$ breaks out and prints (1 print). $P_{1}$ continues with $i = 1$ .
Iteration $i = 1$ : $P_{1}$ forks $P_{2}$ . $P_{1}$ breaks out and prints (2 prints so far). $P_{2}$ continues with $i = 2$ .
Iteration $i = 2$ : $P_{2}$ forks $P_{3}$ . $P_{2}$ breaks out and prints (3 prints so far). $P_{3}$ continues and $i$ becomes 3.
For $P_{3}$ the condition $i < 3$ is false, so it leaves the loop normally and prints (4 prints in total). $P_{3}$ forks nothing more.
Only one process stays in the loop at each level, so the processes form a chain $P_{0} \to P_{1} \to P_{2} \to P_{3}$ , not a tree. Each of the four processes reaches printf exactly once. Total prints $= 3$ (parents that break) $+ 1$ (last child) $= 4$ .

KEY IDEA

Here the child continues the loop and the parent breaks out. So the processes form a chain, with one new process per iteration, instead of the doubling that happens when every process keeps looping. The count is the number of loop iterations plus the original process: $3 + 1 = 4$ .

WATCH OUT FOR

Treating this like the usual for loop with fork(), where the number of processes doubles each iteration, and answering $2^{3} = 8$ . The break in the parent and the continue in the child stop the tree from growing.

From the GATE 2026 CS1 paper. Every question of this paper · Download the full paper · All 9 Processes & threads questions, with notes

GATE 2026 CS1 Q.63: solution and answer

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