int x = 3;
while(x 0) {
fork();
printf("hello");
wait(NULL);
x--;
}The total nu

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GATE-CS is a competitive examination conducted in India. This question is from the 2024 GATE-CS Operating Systems paper.

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Question

int x = 3;
while(x > 0) {
    fork();
    printf("hello");
    wait(NULL);
    x--;
}The total number of times the printf statement is executed is _______

Accepted Answer

Answer: 14Concept -- fork() and Process Tree (from Silberschatz, Galvin, Gagne, Operating System Concepts):Each fork() doubles the number of running processes. The wait(NULL) causes a parent to wait for its child to complete before proceeding. The loop runs while x > 0, decrementing x each iteration.At x=3: 1 process calls fork() --> 2 processes. Both print 'hello' (count: 2). Parent waits for child. Child runs loop.Child at x=3 (same state): forks --> 2 child-processes. Both print (count: +2=4). Child-parent waits. Grandchild runs loop.Grandchild at x=3: forks --> 2. Both print (count: +2=6). Great-grandchild runs loop.This branching continues. Let T(x) = total number of printf calls for a process starting with loop variable x.T(0) = 0. T(x) = 2 + 2*T(x-1) for x > 0 (two processes each print once, then two child processes each run T(x-1)).Wait -- more carefully: each process with value x forks into parent and child. Both iterate: parent waits for child, child recursively forks. T(x) counts total prints from a single process with value x.T(1) = 2 (fork, both print, child does nothing more at x=0). T(2) = 2 + 2*T(1) = 2+4=6. T(3) = 2 + 2*T(2) = 2+12=14. Total = 14.

int x = 3; while(x > 0) { fork(); printf("hello"); wait(NULL); x--; }The total number of times the printf statement is executed is _______

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int x = 3; while(x > 0) { fork(); printf("hello"); wait(NULL); x--; }The total number of times the printf statement is executed is _______

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int x = 3; while(x &gt; 0) { fork(); printf("hello"); wait(NULL); x--; }The total number of times the printf statement is executed is _______

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More Questions from System Calls

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int x = 3; while(x &gt; 0) { fork(); printf("hello"); wait(NULL); x--; }The total number of times the printf statement is executed is _______

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More Questions from System Calls

Frequently Asked Questions

int x = 3; while(x > 0) { fork(); printf("hello"); wait(NULL); x--; }The total number of times the printf statement is executed is _______

int x = 3; while(x > 0) { fork(); printf("hello"); wait(NULL); x--; }The total number of times the printf statement is executed is _______