Shutdown Program for Ubuntu Linux in C

Shutdown C Program for Ubuntu Linux:

#include 

 int main() {

  system("shutdown -P now");

  return 0;

} 

You need to be logged in as root user for above program to execute otherwise you will get the message shutdown: Need to be root, now specifies that you want to shutdown immediately. '-P' option specifes you want to power off your machine. You can specify minutes as:
shutdown -P "number of minutes"
For more help or options type at terminal: man shutdown.