Question

2. Calculate number of times hello is printed.

#include <stdio.h>

#include <sys/types.h>

int main() {
fork();

fork();

fork();
printf("hello\n");

return 0;
}

Answer 1

The image above shows how the fork() calls will be executed in this case, and how many copies of each process will be made. Clearly, as shown above, there are a total of 8 calls made at the end. The printf() statement exists right at the end of the program hence it executes AFTER all the child processes have been created.

A brief summary:

1. The parent process makes one fork() call, which means we now have two processes.
2. Now, each process now makes a fork() call, which means we have two copies of the two processes ie 4 processes.
3. The final fork() call is made, then we have two copies of the four processes i.e. 8 processes.

When we execute the code above, we get:

Which establishes that the number of times the printf() statement is called is indeed 8.