GATE CSE 2026 | Set 1 | Question: 53

Question

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)

Comments

Diagram to visualize how each process is created and where it eventually prints.

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if (fork() == 0)  -----> here fork function is called and its return values those of parent and child processes are being tested

(reminder for me )

Answer 1

 

 

• At i=0: The original parent process forks.

  • The parent gets a non-zero return value, fails the "if"condition, run "break", and prints Hello! (1st print).

  • The child gets a 0 return value, executes "continue", and moves to i=1.

 

• At i=1: The child process forks again.

  • The parent (child of the first step) hits "break" and prints Hello! (2nd print).

  • The new child executes "continue" and moves to i=2.

 

• At i=2: That child forks a last time.

  • The parent hits "break" and prints Hello! (3rd print).

  • The final child executes "continue", which increments i to 3. Since the loop condition i < 3 is now false, it exits the loop naturally and prints Hello! (4th print)

Comments

thnx buddy...

Answer 2

 

Answer 3

The key here is how the if-else logic inside the loop interacts with the fork() return values:

• fork() == 0 (Child): Executes continue, meaning it goes to the next iteration of the loop.

• fork() > 0 (Parent): Executes break, meaning it exits the loop immediately and goes to the printf.

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Step-by-Step Trace

1. Start: We begin with 1 Parent Process ($P_0$) at $i=0$.

2. Iteration $i = 0$: * $P_0$ forks.

   • Parent ($P_0$): Receives a positive PID, hits break, exits loop $\rightarrow$ Prints "Hello!" (1).

   • Child ($C_1$): Receives 0, hits continue, goes to $i = 1$.

3. Iteration $i = 1$:

   • $C_1$ forks.

   • Parent ($C_1$): Receives a positive PID, hits break, exits loop $\rightarrow$ Prints "Hello!" (2).

   • Child ($C_2$): Receives 0, hits continue, goes to $i = 2$.

4. Iteration $i = 2$:

   • $C_2$ forks.

   • Parent ($C_2$): Receives a positive PID, hits break, exits loop $\rightarrow$ Prints "Hello!" (3).

   • Child ($C_3$): Receives 0, hits continue, loop ends (since $i < 3$ is now false) $\rightarrow$ Prints "Hello!" (4).

Answer 4

go classes

Answer 5

https://www.youtube.com/live/IUAIytbb2mw?si=grlYPQnCmeUjcNYn&t=8331    sachin sir's explanation...