The purpose of this assignment is to familiarize you with using the computer and with the mechanics of preparing and submitting assignment solutions. This assignment carries no grade, but you must do the electronic submission. Even if you're already a computer whiz, you might learn something! Your goal this week is to learn to use emacs for editing files, netscape for browsing the World Wide Web, lcc for compiling programs, and /u/cs126/bin/submit for submitting programs.

Your assignment is to create, compile, and run the following extension of everybody's first C program (Kernighan and Ritchie, pp. 5-8).

#include <stdio.h>

main() 
  {
    int n;
    printf("Hello world! Give me a number:\n");
    scanf("%d", &n);
    printf("Thanks! I've always been fond of %d\n", n);
  }

Completing this assignment involves the following steps.

• Log in to a SUN Unix machine. If you're the least bit unsure about using a computer, use one of the machines in room 101 in the CS building. Detailed instructions on what to do on these machines are given below, and there will be people there to answer your questions this week. If you're used to using arizona via remote login, feel free to do so, but you may need to make some minor adjustments in the directions that follow.
• When you log in, the computer starts the "Common Desktop Environment", which is a graphical user interface based on X Windows. You'll see a "Control Panel" along the bottom of the screen, and a "File Manager" window somewhere else on the screen. A tutorial window may also appear. There are lots of "Help" menus; click on a few to see what's available.
• In the left side of the Control Panel, you'll see an icon that depicts a pencil and a piece of paper. There should be a triangle above this icon; click on the icon and a pop-up menu should appear. Select "Terminal" and click the left mouse button.
• You should now have a "Terminal" window somewhere on the screen. You can enter commands by typing the commands in this or any Terminal window followed by the "Enter" or "Return" key.
• For your first command, type emacs hello.c & to create a window for the emacs text editor, ready for you to type in the file hello.c (the & means to run emacs in the background, so that you can type other commands without leaving emacs). emacs is a bit more complicated than the standard Text Editor on the desktop, but much more powerful, and you will be able to use emacs in terminal or telnet sessions on your own computer. If you've used text editors before, you will know how to use emacs. Just use the pull-down menus and the mouse. You can also run a tutorial (look at the Help menu). Enter the program exactly as it appears above. If you omit even a comma, the program won't work. You can use the Tab key or spaces to get the indentation. When you're done, save the program in a file named hello.c.
• Now type lcc hello.c in the Terminal window. This command runs the C compiler, lcc, which compiles hello.c and leaves an executable file named a.out in your directory. If lcc complains in some way, you mistyped something, and you should check your program carefully and get help if you can't see the mistake.
• Type a.out in the Terminal window. This command executes your program. You should get

  Hello world! Give me a number:

  in the Terminal window. Then nothing will happen. You must type a number (say, 5), and hit Enter, then you will get

  Thanks! I've always been fond of 5

  and the program should terminate. You may need to repeat this edit-compile-execute cycle a few times before it all goes smoothly.
• Once you have hello.c working, submit it by typing the following command:

  /u/cs126/bin/submit 0 hello.c

• You will want to check that everything is properly submitted. To do that, type

  /u/cs126/bin/submit 0

• To get a printed copy of your program, type lpr -Ppsr hello.c. You can also click on the Printer icon in the Control Panel.

When you've finished this assignment, try out some of the other software you'll be using this semester. To browse the COS 126 Web pages, type netscape &, click on netscape's Open button, and enter

http://www.cs.princeton.edu/courses/cs126/

in the pop-up dialog box. Cruise around the COS 126 Web; it is essential that you understand what's where and how to get to it.

You'll also use electronic mail a lot this semester. So, to get started, send electronic mail to cs126 telling us (briefly) whether or not you have previous programming experience, in which department at Princeton you might major, and anything else you'd like to say. If you've never used mail, type pine to get started, and ask for help if you get stuck.

To log out, position the mouse over the background, i.e., not over any windows, click the right mouse button, and select "Logout". Alternatively, you can just click the "EXIT" button in the Control Panel. Don't forget to log out!