The purpose of this assignment is to familiarize you with the mechanics of preparing and submitting assignment solutions. This assignment carries no grade, but you must do the electronic submission. Follow these instructions if you want to work on the the arizona system, which runs the Solaris operating system on Sun workstations. We provide different instructions if you prefer to use a Windows or Mac OS X system. Your goal this week is to learn to use emacs for editing files and gcc for compiling programs.

Your assignment is to create, compile, run and submit three short C programs. In addition, you will edit and submit a descriptive file called readme.txt with each of your assignments. (Instructions for the readme file are on the checklist for each assignment.)

PROGRAM 1 hello.c : Create, compile, run and submit the following extension of everybody's first C program.

#include <stdio.h>

int main(void) {
    int num;
    printf("Hello world! Give me an integer:\n");
    scanf("%d", &num);
    printf("Thanks! I've always been fond of %d.\n", num);
    return 0;
}

PROGRAM 2 hello-while.c : Create, compile, run and submit Hello World Exercise #5.

PROGRAM 3 hello-if.c : Create, compile, run and submit Hello World Exercise #6.

Completing this assignment involves a number of steps that are described below. The instructions refer to Program 1, but will be the same for Programs 2 and 3.

Log in to a machine on the arizona cluster. Experienced users can can login remotely to arizona via a telnet or ssh session to arizona.princeton.edu - you can learn more about working on arizona remotely here. Unix novices should use one of the workstations in arizona lab. There will be trained staff there to answer your questions.

• When you log in, you will be asked for your username and password. Then you may be asked to choose a desktop environment. Choose the "Common Desktop Environment". It is a graphical user interface based on X Windows. You should 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. If you were unable to log in, find a lab TA and they will assist you.

• To open a terminal window, click the right mouse button once (and release) in an empty area of the display, then click the left mouse button on the menu entry for "Tools", then click the left mouse button on the sub-menu entry for "Terminal".

• You should now have a "Terminal" window somewhere on the screen. It will have a command prompt that looks something like:

  phoenix.Princeton.EDU% 

  Don't worry if it looks a little different, or the name phoenix is replaced by something else that reminds you of Arizona. You can enter a command by typing it in the Terminal window followed by the "Enter" or "Return" key.
• For your first command, type the text in bold at the command prompt:

  phoenix.Princeton.EDU% source /u/cs126/bin/setup126-f02

  This customizes several Unix tools specifically for COS 126. (Specifically, it adds /u/cs126/bin to your path, copies our .emacs file to your directory, and creates a dummy web page for you, unless you already have one. If most of this sounds like gibberish, don't worry about it. )

Now you are ready to write your first program.

• To begin the process, type

  phoenix.Princeton.EDU% 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. The emacs editor is a bit more complicated than the standard Text Editor on the desktop, but much more powerful, and includes special features designed for writing C programs. 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 launch a tutorial from the Help menu.

• Enter the C program exactly as it appears above. If you omit even a semicolon, the program won't work. Use the Tab key to get the proper indentation. When you're done, save the program in a file named hello.c.

• It is now time to convert your C program into machine executable code. Type

  phoenix.Princeton.EDU% gcc126 hello.c

  in the Terminal window. This command runs the C compiler, gcc, which compiles hello.c and leaves an executable file named a.out in your directory. We use gcc126 instead of gcc to ask the compile to output additional warnings: novice and veteran programmers will find this invaluable. If gcc complains in some way, you mistyped something, and you should check your program carefully. Ask for help if you can't see the mistake.

• In the Terminal window, type

  phoenix.Princeton.EDU% a.out

  This command executes your program. You should get

  Hello world! Give me an integer:

  in the Terminal window. Then nothing will happen. You must type an integer (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.

• To get a printed copy of your program, type the following command in the Terminal window.

  phoenix.Princeton.EDU% lpr hello.c 
  

This sends it to the Print Release Station in Friend 016. You then need to login to the Print Release Station using your OIT NetID and NT password. Select your job from the queue and click PRINT to actually send it to the printer sitting next to the Print Release Station. (Note: If you don't know the difference between your NT password and your email or Unix password, the helpdesk at OIT can solve the mystery.)
• Working remotely. The lpr command sends your file to the Print Release Station in Friend 016. You then need to go to the Print Release Station and release the file to the printer as described in the preceding paragraph. Instead, you can transfer the desired files to your computer (e.g., with ftp or samba) and then print as usual under Windows or Mac OS.

• Once you have hello.c working, submit via the Web. To do this type

  phoenix.Princeton.EDU% netscape &

  and click on netscape's Open button, and enter

  http://www.princeton.edu/~cs126

  choose the Assignment Submission menu option, and follow the instructions provided.

• You will receive an email confirmation of your submission.

• Working remotely. You will not be able to run netscape from a telnet sessions. Instead use the web browser on your computer.

• The final part of the assignment is to browse the COS 126 Web pages. The address is:

  http://www.princeton.edu/~cs126

  Cruise around the COS 126 Web site; it is essential that you understand what's where and how to get to it. Be sure to fill out the online questionnaire. Also make sure you find the "Assignment 0 Checklist" page, and also be sure to read the COS 126 Collaboration Policy.

• To log out, position the mouse over the background, i.e., not over any windows, click the right mouse button, and select "Logout". Don't forget to log out!

• Working remotely. Type the command "logout" when you are finished.