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. Your goal this week is to learn to use emacs for editing files, gcc for compiling programs, and submit for submitting assignments.

Your assignment is to create, compile, and run the following extension of everybody's first C program.

#include <stdio.h>

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

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 trained staff there to answer your questions this week. If you're used to using arizona via remote login, feel free to do so, but you will need to adjust 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 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 "Programs", then click the left mouse button on the sub-menu entry for "Terminal".

• You should now have a "Terminal" window somewhere on the screen. You can enter commands by typing the commands in the 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). The emacs editor 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 launch a tutorial from the Help menu. Enter the C 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

  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. If gcc 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 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.
• Once you have hello.c working, submit it by typing the following command:

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

• If this were a real assignment, you might want to check that everything was submitted properly. To list all the files that you have submitted already for Assignment 0, type

  /u/cs126/bin/submit 0

• To get a printed copy of your program, type

  lpr -Ppsr hello.c

in the Terminal window. Alternatively, click on the Printer icon in the Control Panel.
• The final part of the assignment is to browse the COS 126 Web pages. To do this type

  netscape &

  and click on netscape's Open button, and enter

  http://courseinfo.princeton.edu/courses/COS126_F2000/

  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. Be sure to fill out the online questionnaire and 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". Alternatively, you can just click the "EXIT" button in the Control Panel. Don't forget to log out!