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

2 times

https://ideone.com/Wb7VoK

Only for last fork it will be created

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@srestha, don't run the program in compiler... it give wrong result

i hope it would be 20.

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9.

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I'm getting 20.
How did you get 9, @deepanshu?

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ans is 20.

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Vikas Verma i miss one fork  completely  while writing question in copy..... 

 

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@Warrior

it is your responsibility to check is it previously asked or not before posting the question.

 

@Deepanshu,@Vikas Verma

you have to check before you attempt, otherwise simply your time will waste due to the discussion

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similar one https://gateoverflow.in/242749/self-doubt

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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