CSC212 Lab 1 2014

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--D. Thiebaut (talk) 09:37, 3 September 2014 (EDT)




This is the first Lab for CSC212, and there are many different little details that you need to get familiar with. In this lab you will

  1. review some Python (just to make sure you remember the logic of programming)
  2. learn how to connect to your class account on beowulf2
  3. learn how to use the emacs editor
  4. create simple Java programs.


Part 1: Python Review


The problem below is taken from CSC111, Homework 10 given Spring 2014. Work out a solution in pair or individually. There is nothing to submit for this part.

Lost Cat

(image from nicepixy.net)

Cats.jpg


The program below is missing its class! And it is also missing its documentation! It used to contain a class defined, with methods and member variables, and a fully developed documentation, but unfortunately all of them got erased.

We do have the output of a run of the program, though, when it still had its class definition. Both the incomplete code and the output are shown below. 


#
# missing class goes here...
#



def getNewCat():
    print( "\nPlease enter the information for the new cat:")
    name = input(       "Cat name?         " )
    age  = int( input(  "Age, in years?    " ) )
    vac  = input(       "Vaccinated (Y/N)? " ).strip().lower()
    vac  = vac in ['y', 'yes']
    neut = input(       "Neutered (Y/N)?   " ).strip().lower()
    neut = neut in ['y', 'yes' ]
    breed= input(       "Breed?            " ).strip()
    
    return Cat( name, age, vac, neut, breed )

def display( L, caption ):
    print( "\n\n"+caption )
    print( "=" * len( caption ) )
    for cat in L:
        print( cat )

def main():
    text="""Minou, 3, Yes, Yes, stray
            Max, 1, Yes, No, Burmese
            Gizmo, 2, No, No, Bengal
            Garfield, 4, Yes, Yes, Orange Tabby"""

    for line in text.split( "\n" ):
        words = line.strip().split( "," )
        if len( words ) != 5:
            continue
        name, age, vaccinated, neutered, breed = words
        age = int( age.strip() )
        if vaccinated.strip().lower() == "yes":
            vaccinated = True
        else:
            vaccinated = False

        neutered = neutered.strip().lower() == "yes"
        
        cat = Cat( name.strip(), age, vaccinated, neutered, breed.strip() )
        try:
            cats.append( cat )
        except NameError:
            cats = []
            cats.append( cat )

    display( cats, "List of cats:" )

    cats.append( getNewCat() )

    display( cats, "List of cats with new addition:" )

    vaccinatedNeuteredCats = []
    for cat in cats:
        if cat.isVaccinated() and cat.isNeutered():
            vaccinatedNeuteredCats.append( cat )

    display( vaccinatedNeuteredCats, "Vaccinated and neutered cats:" )
    
    
main()


Output


List of cats:
=============
Cat: Minou, age: 3, vaccinated, neutered (stray)
Cat: Max, age: 1, vaccinated, not neutered (Burmese)
Cat: Gizmo, age: 2, not vaccinated, not neutered (Bengal)
Cat: Garfield, age: 4, vaccinated, neutered (Orange Tabby)

Please enter the information for the new cat:
Cat name?         Ralph
Age, in years?    4
Vaccinated (Y/N)? y
Neutered (Y/N)?   y
Breed?            Angora


List of cats with new addition:
===============================
Cat: Minou, age: 3, vaccinated, neutered (stray)
Cat: Max, age: 1, vaccinated, not neutered (Burmese)
Cat: Gizmo, age: 2, not vaccinated, not neutered (Bengal)
Cat: Garfield, age: 4, vaccinated, neutered (Orange Tabby)
Cat: Ralph, age: 4, vaccinated, neutered (Angora)


Vaccinated and neutered cats:
=============================
Cat: Minou, age: 3, vaccinated, neutered (stray)
Cat: Garfield, age: 4, vaccinated, neutered (Orange Tabby)
Cat: Ralph, age: 4, vaccinated, neutered (Angora)


Question

Recreate the original Python program with its Cat class. Make sure that it will generate the same output shown above if fed the same cat information.


Solution






Part 2: Connection to a Remote Computer Server: Beowulf2


In this section you will learn how to connect to a remote computer and work on it using the shell, or Terminal. The server for the CS department is called beowulf2. Its address is beowulf2.csc.smith.edu.


Using a Shell or Terminal


There are 3 different ways for you to connect to our server:

  • From a Linux computer in FH342
  • From a Mac laptop
  • From a Windows laptop.


Whatever computer you have, it is good for a computer science to be familiar with more than one way to connect to remote computers. Try to use different methods during the semester.

For Windows PCs, Additional Software is Needed


If you're using a Windows PC, go to https://www.smith.edu/smithsoftware/index.html and download the SSH package after having read the installation instructions.

SmithCollegeSoftwareDownloadSSH.png


  • You should get a file called ssh.exe in your Download folder.
  • Double click on it and accept all the default answers to installation questions. You should end up with 2 new icons on your desktop:


SshIconsWindows.png


  • Once installed, double click on the blue icon (ssh), and then on Quick Connect
  • Enter your login information from the CSC212 account sheet.
  • Click Yes
  • Enter your password
  • Et voilà!


SshWindowOnWindows.png



  • You're ready to start working on Beowulf2!


Mac Users: Use Terminal


  • Open a terminal window and type the following command at the prompt:


ssh 220a-xx@beowulf2.csc.smith.edu


  • replace xx by your 2-letter Id.
  • provide your new password when prompted
  • You should end up with a screen similar to this one:


MacTerminalSSHBeowulf2.png


Connection From a Linux Computer


To login refers to the action of connecting to the computer as a user. To connect to Beowulf2, the computer used for Computer Science classes, one must have an account and a password. Logout is the term used when you are finished with the computer and want to terminate your session.

You should have a Unix account form at this point, and have found on it

  1. your account name (of the form 212a-xx, where xx are two letters, different for everybody),
  2. and your password.


If the Quick Connect window is not greeting you, click on the Quick Connect icon to get it:

Enter beowulf.csc as the host name, 212a-xx as your user name (change the xx to reflect your 2-letter Id) Click on the Connect button Enter your password. and click "Connect".

If everything went well, you should see this: 

SSH Secure Shell 3.1.0 (Build 235)
Copyright (c) 2000-2001 SSH Communications Security Corp - http://www.ssh.com/

This copy of SSH Secure Shell is a non-commercial version.
This version does not include PKI and PKCS #11 functionality.

[212a-xx@beowulf ~]$

Keep your account and password information in a safe place, or learn both by heart! You will need them every time you need to use your account and work on your homework assignment or lab.

You may want to log out now, to practice this login procedure a couple times. If you are working with a lab partner, it is a good time to log out and let her/him try the procedure.

To logout of the session with beowulf, simply type exit at the Linux prompt: 

 [212a-xx@beowulf ~]$  exit

Don't hesitate to call on the TA or your instructor if you need help.




Part 3: Playing with emacs


In order for you not to suffer from a misbehaving backspace/delete key as happened in class yesterday, you should execute the following command (your input is in bold face) 

  [111c-xx@beowulf ~]$  getcopy .emacs
  cp: overwrite `./.emacs'? y

(That is "getcopy" space period "emacs") It's a configuration file that will allow emacs to understand the backspace key correctly. You only need to do this once and you will be set for the semester.

You will now get a copy of a file from your instructor's account, and edit it. The file is called Fulghum and is a short story from Robert Fulghum's book All I really need to know I learned in Kindergarten.

To get a copy of this file, type 


  [111c-xx@beowulf ~]$  getcopy fulghum


followed by the return key. Then edit the file with the command 


  [111c-xx@beowulf ~]$  emacs fulghum


Simply work on the first paragraph of the file, and try to straighten it up. I have indicated below, on the right-hand side, which emacs commands you can use to fix the text on your screen.

Fulghum emacs.jpg

When you are done with the modification, or if you want to stop for right now and save your modifications, type C-x C-c, and press y when emacs asks if you want to save the file. Below is a summary of some useful emacs commands.

You should find some time this week to go to a lab and read the Emacs at Smith handout while in front of the terminal, on your own. This is the best way to test and learn the different features of the editor!

DEL/Shift Backspace Delete previous character
c-d Delete character at cursor
Esc-d Delete word
c-k Kill line
c-a Go to beginning of line
c-e Go to end of line
c-f Move cursor 1 character forward
c-b Move cursor 1 character backward
c-p Move to previous line
c-n Move to next line
c-x c-c quit emacs and save file
c-x c-s save file but remain in emacs
c-g GE OUT OF TROUBLE!

Part I of the homework assignment for this week is to edit the complete story about Larry Walters and his flight over Los Angeles.


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