ISRO2017-51

Question

Wha is the output of the following program?

main()
{
    int a = 10;
    if(fork()) == 0))
        a++;
    printf("%d\n",a);  
}

• A. 10 and 11
• B. 10
• C. 11
• D. 11 and 11

Comments

When fork() is called, a new process is created and fork()returns 0 to the child process and the process-id of the child process to the parent and as such the child will only execute a++ as it has 0 value, so for the parent a=10 and for the child a=11. refer to this https://www.geeksforgeeks.org/fork-system-call/

Answer 1

when parent process come across fork(),it creates a child processes.

in the multiprogramming environment,there is no order of execution defined.

a child process can be executed first or a parent process can be executed first.

so,the answer could be either  10 and 11 

                                              or 11 and 10.

 

if the question is msq type,then select both 10 and 11 ,11 and 10.

 

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is my intution correct for following?

what is the value printed by child process ? 

will the “if condition” will be evaluated by child process or

 child process directly executes line 3?

main()
{
   1. int a = 10;
   2. if(fork()) == 5)) //not fork()==0
   3.    a++;
   4. printf("%d\n",a);  
}

since,a single line is converted into multiple machine level instructions,

so, the if condition will be evaluated and “if condition” fails.so,the value printed by child process is 10.