how to know parent or child process in vfork function

Question

I wonder if we use vfork , how we know child process or parent process , since the resources are shared . to be more specific , assume the following code :

int main()
{
    int pid = vfork();
    if(pid == 0)
    {
       // code for child
     }
    else 
    {
       // code for parent
    }
    return 0;

}

in the code above , if the resources are shared , then pid variable will have uniqe value , so is this code is valid ? , since i have seen examples do things as the above code .

Answer 1

vfork() suspends the parent until the child either calls exec*() or _exit().

using vfork() in this format as we use fork() results in program run in infinite loop. it doesn't end.
read this discussion to get better idea about using vfork().

Answer 2

In vfork the parent will wait the child to finish, so there is no need to differentiate.

Answer 3

is this code is valid ?

Yes. vfork() still will make a copy of parent process (conceptually), and as normal fork(), in the child process it will return 0, in the parent process the pid of that child process.