Hello World!

Do you want to make your computer do that?
Here's how!

First, go to a CS machine in the Sol or Vega labs.
Login to a machine, using your name and password.
Open up an Xterm window by pointing on a free space on the desktop and clicking on the left mouse button and choosing 'Xterm'
Open up an Emacs window by selecting it on the menu, or by typing emacs ~/hello.C
in the Xterm window.

This will set up an emacs window, from which you can do your editing.

Now, enter the following code into the emacs window:
#include <iostream.h>

main() {
cout << "Hello World!\n";
}
You have entered in the program! Now save it.
To save: hit ctrl-x and then hit ctrl-s
To save and exit: hit ctrl-x and then ctrl-c. The computer will then ask:
'Save file ...? (y,n,...)' you answer, 'y'
You don't have to exit Emacs- you may edit new documents by typing Ctrl-x, Ctrl-f inside of Emacs.

You now have a file called hello.C in your directory

In the xterm window, type g++ hello.C
After a few seconds, the gnu C++ compiler will create a file in the directory called a.out
type a.out
The computer should output "Hello World!"

Another way to compile your program, is to use the make utility

If you have an Emacs window active, go to it and hit Ctrl-x Ctrl-f, then enter Makefile. Skip over this next bullet if you open up Makefile from within Emacs
Inside an X-term Window, type emacs ~/Makefile
Enter the following program into the emacs window
Important: Formatting in makefiles is important. Please put return characters in between rules and put TAB characters in front of command lines. For example, $(CC) -o test hello.o must begin with a TAB.

#set up compiler and options
CC=g++

###
# test
###

test: hello.o
$(CC) -o test hello.o

hello.o: hello.C
$(CC) -c hello.C
Save Makefile (Ctrl-x Ctrl-c)
Leave emacs and click on an active Xterm window
Type make test
There is now a file called test in your directory, and is executable
Type test
Your computer should output "Hello World"

That's the end of this tutorial. Good luck with your first homework.

Last modified: Mon Sep 8 17:48:49 1997 by Marc Dreyfuss