How to write a program in c program that shuts down a computer in 20 seconds

Why in C? Easier in a batch file!

shutdown /t 20

Or just create a shortcut on the desktop using


s shuts it down and the 00 is the countdown timer in seconds.

for a complete list of options for the dos commands look here http://pcsupport.about.com/od/commandlinereference/p/sh...

Sounds suspiciously like a class assignment.

lol yea. On a related note, can anyone tell me how to program a "Hello World" message?

EDIT: Thought I better add a j/k to prevent any questions on what language I need it in hehe.

http://www.invatac.com/2012/09/how-to-write-program-in-...

There is a application already for this   DShutdown it does exactly what you want and more.

By a timer, time of day, when a application closes, whatever. It can Shutdown, sleep, suspend, hibernate etc etc...