Question

Hey i want to know what will be output of following code:-

main()
{
fork();
fork();
fork();
printf("hello world");
}

I think it should print hello world 4 times.
Plz help me.

Answer 1

It will print it 2^3=8 times. Remember, every time you call fork, you are creating a child process, that child process will continue the execution from right after it got forked so it can itself also fork. The tree will look like this.

                  First process.

  Forked1               Forked2       Forked3

Forked4—Forked5 ————– Forked6

Forked7

So we will have total of 8 process (main process and 7 forked processes)running and printing the print statement.
As a side note: if the print statement was before a fork, it would not get executed by newly forked process.