CS : Programming for Non-majors, Spring 2003 Programming Project #1: Thinking of a Number Due by 10:20am Monday January

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1 CS : Programming for Non-majors, Spring 2003 Programming Project #1: Thinking of a Number Due by 10:20am Monday January This first assignment will help you learn to use the Linux computers administered by Engineering Computing Services (ECS). An account should have been set up for you automatically. If you have trouble accessing your account, then you should contact Dr. Neeman by no later than Wednesday January 22. You must be enrolled in CS1313 to get an account. Actions and commands that you should perform or type are in the computer boldface font. Your user name is denoted here as yourusername, but will actually be your OU4+4 ID (the first 4 letters of your last name in all lower case, followed by the last 4 digits of your OU student ID). The requirements for this assignment are: 1. Connect and log in, from a computer that you re sitting at, to any one of these computers: kennedy.ecn.ou.edu, lincoln.ecn.ou.edu, or roosevelt.ecn.ou.edu. (a) From a PC in Carson 206: i. Press Ctrl - Alt - Delete simultaneously. This will pop up a welcome window; click OK or press Enter. Log on to ECS2000 using your OU4+4 account. ii. The Start button will appear in the lower left corner of the screen. Click on it and traverse the menus like so: Start Programs General Software Putty SSH Client iii. On the left side of the PuTTY Configuration window, under the heading Terminal is an entry Keyboard; click on it. This will bring up a section titled Options controlling the effects of keys. Under this is a heading called Change the sequences sent by: and beneath that is The Backspace key. Select Control-H. Somewhat below this is The Function keys and keypad. Select Xterm R6. iv. On the left side of the PuTTY Configuration window, below Terminal and its subentries, is an entry Window; click on it. This will bring up a section titled Options controlling PuTTY s window. The first option is Set the size of the window. You may choose as many rows as you like (40 is recommended), but you should make sure to choose 80 columns. v. On the left side of the PuTTY Configuration window, the first entry is Session; click on it. This will bring up a section titled Basic options for your PuTTY session. The first option is Specify your connection by host name or IP address, and immediately below it is Host Name (or IP address). In the text box immediately below that, type the full name of the computer you are logging into (lincoln.ecn.ou.edu, kennedy.ecn.ou.edu or roosevelt.ecn.ou.edu). Immediately below this is Protocol; select SSH. vi. At the bottom right of the PuTTY Configuration window, click Open. vii. If a PuTTY Security Alert window pops up, click Yes. viii. Log in using your OU4+4. 1

2 (b) From elsewhere using a Windows PC: you will need to download the PuTTY SSH client onto your desktop, which is available at: Once you ve downloaded it, the process should be the same as above. (c) From elsewhere using a Unix/Linux computer: you should be able to access the command ssh from the Unix command line, like so: % ssh yourusername@whatever.ecn.ou.edu where whatever is one of lincoln, kennedy, or roosevelt. 2. Once you log in, you ll get some text, and then a Unix prompt probably a percent sign with the cursor after it, like so: % There may be some information before the prompt character, such as the name of the computer that you ve logged in to, your user name, etc. For purposes of CS1313 course materials, we ll generally use the percent sign % to indicate the Unix prompt. 3. If, immediately above the Unix prompt, there are lines of text that read something like: No directory /coe/std/student0/yourusername! Logging in with home = "/". then you should log out immediately and log in to one of the other computers listed above (roosevelt, lincoln, or kennedy). 4. Check to make sure that you re in your home directory: % pwd /coe/std/student0/yourusername This command means: Print working directory; i.e., print the full name of the directory that I m currently in. If your current working directory is just a slash (which means the root directory), rather than something like /coe/std/student0/yourusername, then you should log out immediately and log in to one of the other computers listed above (roosevelt, lincoln, or kennedy). Note that a directory in Unix is like a folder in Windows or MacOS. 5. At the Unix prompt, type exactly the bold text below, excluding the percent sign, which indicates the Unix prompt (all commands should be followed by pressing Enter ): % cp ~neem2345/.login.student ~/.login This command means: Copy the file named.login.student that s in Dr. Neeman s home directory to my home directory, and name my copy.login. Notice: The Unix copy command is cp. The first filename after cp is the source; the second is the destination. Dr. Neeman s account name on the ECS computers is neem2345 rather than hneeman. The filenames.login.student and.login both begin with a period (very important). They are pronounced dot login dot student and dot login, respectively. In Unix, pieces of a filename are separated by slashes, not by backslashes as is the case in Windows. The symbol (called a tilde, pronounced TILL-duh ) denotes your home directory. 2

3 The substring neem2345 means the home directory of the user named neem2345. If for some reason this does not work, try % cp /coe/fsr/facst0/neem2345/.login.student ~/.login You will NOT have to do this for future logins. 6. Type the following command: % source ~/.login This command means: Execute the Unix commands that are in the file named.login, which is in my home directory. You will NOT have to do this for future logins. 7. Create a subdirectory named CS1313, like so: % mkdir CS1313 NOTICE: in the subdirectory name CS1313, the CS should be CAPITALIZED; i.e., the directory s name is capital-c capital-s one three one three with no spaces or other characters in between. This command means: Create a directory named CS1313 as a subdirectory inside the directory that I m currently in. You will NOT have to do this for future logins. 8. Set the permissions on your CS1313 directory so that only you can access it: % chmod u=rwx,go= CS1313 This command means: Change the mode (list of permissions) on my subdirectory named CS1313 so that I (the user) can read files in it, write files in it, and go into (execute) it, but nobody else can. Your CS1313 directory is now accessible only to you. The only other people who can access it are the system administrators (called sysadmins for short) of these computers; i.e., the staff of Engineering Computing Services ( The instructor and TAs CANNOT access your CS1313 subdirectory; nor can any of your CS1313 classmates. You will NOT have to do this for future logins. 9. Log out of the Linux computer by typing exit. Then log back in again. Once you have completed Steps 4 through 8 above, you won t have to do them again when you log in later. 10. Go into your CS1313 directory: % cd CS1313 This command means: Change the current directory to CS1313, which is a subdirectory of the current directory. NOTE: ALL CS1313 project files should reside in your CS1313 subdirectory, for this and ALL future programming projects. 11. Check to make sure that you re in your CS1313 directory: % pwd /coe/std/student0/yourusername/cs Aside: to learn more about a particular Unix command, type: % man commandname For example, try % man chmod which will give you the online manual page for the chmod command. The output of man goes through another command, more, which shows one screenful at a time. To get the next screenful, press the spacebar; to get the next line, press Enter. To quit, press Q. 3

4 13. Copy the Fortran 90 source file named my number.f90 from Dr. Neeman s home directory to your CS1313 directory: % cp ~neem2345/my number.f90. This command means: Copy the Fortran 90 source file named my number.f90 from Dr. Neeman s home directory to the directory that I m currently in. Notice the period at the end of this command; it means the directory that I m currently in and is very important. 14. Confirm that you have my number.f90 in your CS1313 directory by listing the directory s contents: % ls my number.f90 This command means: List the names of the files and subdirectories in my current working directory. Note that the command is ell ess rather than one ess. 15. Copy the make file named makefile from Dr. Neeman s home directory to your CS1313 directory: % cp ~neem2345/makefile. Again, notice the period at the end of this command. 16. Using the text editor of your choice (e.g., pico, vi), edit my number.f90: % pico my number.f90 This command means: Edit the text in the file named my number.f90 that s in my current working directory, using the text editor program named pico. Your TA will be happy to help you learn how to use the pico editor, which is a lot easier to learn than the vi editor. Notice the little help messages at the bottom of the screen: ^G Get Help ^O WriteOut ^R Read File ^Y Prev Pg ^K Cut Text ^C Cur Pos ^X Exit ^J Justify ^W Where is ^V Next Pg ^U UnCut Text ^T To Spell For example, ˆW Where is means that you should press Ctrl - W (the caret ˆ indicates the Ctrl key) to search for a particular string of characters; ˆC Cur Pos is short for Cursor Position and causes pico to tell you what line number the cursor is located at; ˆK Cut Text means delete the line that the cursor is currently on. 17. Using the text editor, make the following changes to my number.f90: (a) In the block of comments at the top of the file, change the author name and address, and the lab information, so that they are your information. (b) In the declaration section, change the constant values assigned to minimum number, maximum number, close distance and computers number. You may select any integer values that you want, as long as they are different from 1, 5, 10 and 1 respectively, and minimum number < computers number < maximum number. (c) In the execution section (also known as the body of the program), change the following output strings to your own words: i. Hey! That s not between ii. That s amazing! iii. Close, but no cigar. iv. Bzzzt! Not even close. Note: you are welcome to say pretty much anything you want, but please avoid foul or inappropriate language. Please be entertaining; we ll have a lot of these to grade. 4

5 18. Every few minutes while you re editing, you should save the work that you ve done so far, in case your work is interrupted by a computer crashing. In pico, type Ctrl - O (the letter oh), at which point pico will ask you, near the bottom of the screen: File Name to write : my number.f90 That is, pico wants to know what filename to save the edited text into, with a default filename of my number.f90. Press Enter to save to the default filename my number.f The lines of text in the Fortran 90 source file my number.f90 should never be more than 80 characters long, and ideally no more than 72 characters long. (Your PuTTY window should be 80 characters across.) Some text editors, including pico, try to help keep text lines short, by breaking a long line into multiple short lines. For example, pico will break a line such as PRINT *, "Why you big old stinker! into two separate lines: That s not between ", minimum_number, & PRINT *, "Why you big old stinker! That s not between ", minimum_number, & That is, pico automatically puts a carriage return after the second comma. Unfortunately, the Fortran 90 compiler will consider this to be an error. Why? For historical reasons 1, Fortran cannot allow an individual statement to use more than one line, unless each line of the statement except the last ends with a continuation character, specifically an ampersand (&), and likewise each line of the statement except the first begins with a continuation character (and possibly some spaces). So, the right way to write the above example is: & PRINT *, "Why you big old stinker! minimum_number, & That s not between ", & 20. Like the lines of Fortran 90 source text, the lines of output text should never be more than 80 characters long, and ideally no more than 72 characters long. You can break a long line of output text into shorter pieces by making it into two PRINT statements. For example: PRINT *, "Why you big old stinker! That s not between ", & & minimum_number, " and ", maximum_number, "!" This single PRINT statement can be converted into two PRINT statements, like so: & PRINT *, "Why you big old stinker! That s not between ", & minimum_number PRINT *, " and ", maximum_number, "!" 21. A character string literal constant, often called a string literal for short, is a sequence of characters between a pair of double quotes or a pair of single quotes. For example, in the PRINT statement PRINT *, "This is a PRINT statement." the following is a string literal: "This is a PRINT statement." We say that the pair of double quotes delimits the sequence of characters in the string literal. 1 Punch cards, which used to be the only way to write a Fortran program, are 80 characters wide. 5

6 In principle, Fortran 90 will allow you to embed continuation characters inside a string literal; for example: "This is an extremely long string literal. & incredibly fascinating just to look at it? & proud of it." Isn t it & I m so & In CS1313, however, you are ABSOLUTELY FORBIDDEN to do this. Instead, you should convert the very long string literal into multiple short string literals, for example by breaking a long PRINT statement into multiple PRINT statements: PRINT *, "This is an extremely long string literal. PRINT *, "incredibly fascinating just to look at it? PRINT *, "proud of it." Isn t it" I m so" 22. After you ve finished editing, exit the text editor. In pico, type Ctrl - X. If you have made any changes since the last time you typed Ctrl - O, then pico will ask you, near the bottom of the screen, Save modified buffer (ANSWERING "No" WILL DESTROY CHANGES)? To save your most recent changes to the file (which is probably what you want to do), press the Y key; to avoid saving your most recent changes, press the N key. After that, pico will behave the same as if you had typed Ctrl - O. 23. Once you have finished editing my number.f90, for your own edification examine the contents of the make file: % cat makefile my number: my number.f90 f90 -o my number my number.f90 This command means: Output the contents of the text file named makefile to the terminal screen. Notice that, on the first line of makefile, between the colon and my number.f90, there is at least one tab character (on most keyboards, it s in the upper left next to Q ), and likewise on the second line there is at least one tab character (and no non-tab characters) preceding the f90 command. 24. Make the executable program: % make my number f90 -o my number my number.f90 Notice: In the make command, the command line argument my number is the name of the executable (the file that can actually be run) that you are making. The make command invokes the Fortran 90 compiler to compile the source file named my number.f90. In the compile command, the command line option -o my number indicates that my number is to be the name of the executable; if that option had been left out, then the name of the executable would be a.out ( the output of the assembler ) by default. 6

7 25. If the program doesn t compile, then you ll need to edit it and figure out where things went wrong. In the worst case, if you re totally stumped, then copy the original from Dr. Neeman s home directory again, and start editing from scratch. 26. Once you have the program compiled, test it by running the executable: % my number Let s see whether you can you guess the number that I m thinking of. It s between 1 and That s amazing! Note: your version will look a bit different from this. 27. Perform a full test of my number, using the following values as inputs, in this order: (a) an integer value less than minimum number (b) an integer value greater than maximum number (c) an integer value between minimum number and maximum number (inclusive), but far from computers number (d) an integer value within close distance of computers number (e) the value of computers number It ll look similar to this: % my number Let s see whether you can guess the number that I m thinking of. It s between 1 and Hey! That s not between 1 and 10! 11 Hey! That s not between 1 and 10! 2 Bzzzt! Not even close. 6 Close, but no cigar. 5 That s amazing! 28. If the program doesn t run, then just as in Step 25 above you ll need to edit it and figure out where things went wrong. Again, in the worst case, if you re totally stumped, then copy the original from Dr. Neeman s home directory again, and start editing from scratch. 29. Once the program compiles and runs properly, then you re ready to create a script file, which is a record of your interactions with the computer. Start the script file: % script pp1.txt Script started, file is pp1.txt Notice that pp1.txt means the text file containing Programming Project #1. IMPORTANT: do NOT use the name of the executable in the name of the script file. Starting a script file is like turning on a tape recorder: every keystroke that you input (including backspaces) and every character that the computer outputs will be recorded into the script file, until you turn it off (see below). 7

8 30. Touch (update the timestamp of) the Fortran 90 source file, using a command that touches all existing Fortran 90 source files: % touch *.f90 This command means: Update the timestamp of every file in the current working directory that ends in.f90. The asterisk (*) is called a wildcard; it means this part of the filename can contain anything, or nothing. If you don t touch your source file, your executable may not compile, in which case you have not proven that your program compiles properly, so YOU WILL LOSE UP TO HALF THE TOTAL VALUE of the project. 31. List the contents of the directory, using the long listing -l option: % ls -l -rwxr-xr-x Jan 29 18:27 my number -rw-r--r Jan 29 19:10 my number.f90 Notice that the command is: ell ess space hyphen ell (lower case L, lower case S, space, hyphen, lower case L); it is not ell ess space hyphen one 32. Output your make file: % cat makefile This command will cause the contents of makefile to be sent to the terminal screen, and also to be saved in pp1.txt, the script file. 33. Output your Fortran 90 source file: % cat my number.f90 As above, this command will cause the contents of my number.f90 to be sent to the terminal screen, and also to be saved in pp1.txt, the script file. 34. Make your executable program: % make my number 35. Run my number, using the same values in the same order as your test in Step 27, above. 36. Terminate the script session: % Ctrl - D Script done, file is pp1.txt This is like turning off the tape recorder. 37. You should now have a script file named pp1.txt that contains a complete record of the scripting session. Check to make sure that you have the file: % ls my number my number.f90 pp1.txt 38. Print your script file. The best way to print from a PC in Carson 206 is to use MS Wordpad: Start Programs Wordpad followed by File Open At the top of the Open window, next to Look in, select: yourusername on washington.coe.ou.edu (H:) Then double click on your CS1313 folder. 8

9 In the text box named Files of type select: All Documents (*.*) Open the file that you want to print (e.g., pp1.txt). Next, at the top of the WordPad window, traverse Format Font and choose Courier New, which is a fixed width font appropriate for computer programs; use a size of 10 to 12. Then traverse File Print Select as your printer either CEC206HP on Tyler or CEC206INK on Tyler. Then click Print. 39. Using a word processor, text editor or typewriter, create and print the following items: (a) A cover sheet with the following information: i. Project number and name ii. Course number, name and semester iii. Author name and address iv. Lab section, day and time For example: Project #1: Thinking of a Number Class: CS Programming for Non-majors, Spring 2003 Author: Lee Kim (leekim@ou.edu) Lab: Section 012 Friday 1:30pm Notice that this information is the same as in the comment block at the beginning of my number.f90. (b) A summary essay about the project, in your own words (see below). Note: the cover should be on a separate page from the summary essay. 40. When you are done, log out of both the Linux computer and the Windows PC. 41. Bind the cover sheet (on top), the summary essay (next), and the pages of the script file in order (last), with at least an adequate staple. No paper clips, duct tape, yarn, etc. The Summary Essay For each CS1313 programming project, the summary essay will be worth at least 10% of the project s total value (i.e., a full letter grade) and should cover the following points: The nature of the problem to be solved An abstract description of the method of solving the problem that you used A list of the concrete steps by which you implemented your method The issues that you had to address during implementation The concepts that you learned from this project References as appropriate: EVERY summary essay must include a references section, which may be marked none if there are no appropriate references. For Programming Project #1, the summary should be at least half a page single spaced, or a full page double spaced, with a font of 10 to 12 points. For future programming projects, the summary may need to be longer. 9

10 Notes READ THIS PROJECT SPECIFICATION SEVERAL TIMES, CAREFULLY. It is YOUR responsibility to read and comply with it. Failure to follow directions will cost you a significant amount of points on this and all assignments. The fact that you didn t notice something will NOT excuse you from complying with it. You will use the same basic process for every programming project in this course. Since your programming projects are 55% of your grade, each one may be worth half a letter grade or more. You ll want to do them all, and to do them well. You are expected to keep a copy of your source code and your script file on your ECS account through the end of the semester. Do not delete either file! If something goes wrong with your printout, these files will be your only proof that you ve done the work. In addition, you may be assigned mini-projects that require you to modify a completed project; if you ve deleted that project, then you may have to do the whole thing from scratch in a very limited amount of time. We strongly recommend that you do NOT attempt extra, unrequested tasks on any assignment. While doing extra work is admirable in principle, in practice it creates a significant chance that you will be unable to complete the assignment on deadline. Unrequested extra work will NOT gain you extra credit. In some cases we may assign bonus work, which will be worth extra credit and which we encourage you to try; otherwise, it may be foolhardy to complicate a given assignment unnecessarily. The perfect is the enemy of the good. To be a good programmer, you need the following: Patience Designing, writing and debugging programs takes a lot of time. Persistence Often, you will find yourself stuck without knowing how to proceed; do not give up. Pessimism Just because you have a design, that doesn t mean it ll be easy to write the program. Just because you ve written the program, that doesn t mean it ll compile. Just because it compiles, that doesn t mean it ll run. Just because it runs, that doesn t mean it ll produce the correct answer. Just because it produces the correct answer, that doesn t mean that the printer works. Practice Just like writing prose, or welding, programming is learned by doing, not by theorizing. 10