Question

I have below some code in C which uses the fork() system call, but I am just confused: how do I go about
solving what it does:

int main()
{
    fork();
    fork() || fork() && fork();
    fork();
    printf("ämit");
}

fork() && fork() || fork(); is evaluated some thing like this below:

       fork()
      /      \
    0/        \>0
 || fork()     && fork()
     /\            /   \
    /  \         0/     \>0
   *    *     || fork()  *
                /   \
               *     *

I need same kind of tree for fork() || fork() && fork(). Can anyone tell me how I should achieve it?

Answer 1

|| has lower precedence than &&, and those operators short-circuit after evaluation of the first operand if it contains sufficient data (|| short-circuits if first operand is true and && short-circuits if first operand is false).

fork()||fork()&&fork() is equivalent to fork() || ( fork() && fork() )

Therefore:

                                                       fork()
                                                     0/     \>0
                                                     /       *  ==> || short-circuits, no evaluation of  fork()&&fork()
                                                   fork()
                                                   0/    \>0
 && short-circuits, no evaluation of &&fork() ==>  *     fork()
                                                         /   \
                                                        *     *

For you first example it was equivalent to ( fork() && fork() ) || fork().