How to make parent process wait till Completion of Child Process (Joining parent with child process)

How to make the parent process wait till the completion of execution of child process. The following C program makes the parent process to wait till the completion of its child process.

#include<stdio.h>
main()
{

How to make Child process an Orphan Process

C program in Linux or Unix to make a child process orphan:

Making child as orphan

#include<stdio.h>
main()
{