Fork System Call

Question

A process execute the code:
 

main()
{
    fork();
    fork() && fork() || fork();
    fork();
    printf("Hi");
}  

The number of times "Hi" will be printed is

Comments

reference :-  https://www.geeksforgeeks.org/fork-and-binary-tree/

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Is the answer 20?

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$Ans: 20$

$ \left((fork()\ \&\&\ fork() )\ ||\ fork() \right)$

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$(p,c4,c8,c2,c6,c1,c5,c9,c3,c7)\times 2=20$

Answer 1

Basic points : -

1) && ===> if left side operand evaluates to 0 then right side operator doesn't evaluate

2) ||   ===> if left side operand evaluates to 1 then right side operator doesn't evaluate

3) fork() ====> Doubling the processes ( one parent copy and one child copy )

4) Precedence of && is grater than precedence of ||

 fork() && fork() || fork() equivalent to  ( fork() && fork() ) || ( fork() ) , note that result of this statement doesn't used for next statement

 

for better clarity of image https://drive.google.com/drive/folders/1aji_OQGkDY9atCk6zwGhl5dYeMWXMm-c

Comments

if(fork())  \\ P>0 , C2=0 , C1>0 , C3=0
 {
        if(fork());  \\ (P>0 , C4=0) , (C1>0 , C5=0)
        else
            fork(); \\ (C4>0 , C6=0) , (C5>0 , C7=0)
}
else
  fork(); 

in the code written by soumya 

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yes, that I was telling. How it could be correct, I am not getting

can u explain a bit?

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now i understood, your problem, how this equivalent code written?

fork() && fork() || fork();

e1 && e2 || e3 ; ===> ( ( e1 && e2 ) || ( e3 ) )

first e1 executed, if it is false then e2 can't executed, go to e3

first e1 executed, if it true, then

           1) e2 executed if it is true, then e3 can't executed

           2) e2 executed if it is false, then e3 executed 

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if( e1 )

{

}

else

{

   e3;

}

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if(e1)

{

          if(e2)

         {

                

         }

        else

        {

             e3;

        }

}

else

{

        e3;

}

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if(fork())

{

          if(fork())

         {

                

         }

        else

        {

             fork();

        }

}

else

{

        fork();

}

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remaining code written as it is

Answer 2

Answer should be 20