Project 1 Number Conversions

5/31/2021 P1 Number Conversions

File Types c

Project 1: Binary and Hexadecimal Conversion
Corrections and Additions
Binary Representation of 5 (0101) had a leading zero. The leading zero was an error and the file
has been corrected. The answer should have been 101. Please re-download the file.
Input data should take either upper case or lower case letters (this has been taken care of in the
provided function). The output should use only uppercase letters.
Our grading script uses the provided version of main. Please write your functions to manipulate the
arrays and do not just use printf() with format strings to manipulate the appearance of the output.
Changed the %d to %u in lines 35, 40, 45 and 50 to use the decimal integer as an unsigned number
instead of a signed number.
#define HEX_STRING_LENGTH should be 11 not 9. (8 hex digits for 32 bit data, + 1 '\0\ character +
'0x' = 11. Math is hard.
Files
1. Number_Translation_Template.c
(https://canvas.wisc.edu/courses/230411/files/18259225/download?download_frd=1)
2. test_input.txt (https://canvas.wisc.edu/courses/230411/files/18114513/download?download_frd=1)
3. test_output.txt (https://canvas.wisc.edu/courses/230411/files/18283525/download?download_frd=1)
Learning Goals
1. Learn some basic Linux commands.
2. Learn to transfer files between computers.
3. Start using a terminal-based text editor of your choice.
4. Become familiar with the build process for a C program.
5. Write a simple C program.
6. Learn how to submit your assignments.
Logistics
1. All work for this assignment is to be done on one of the UW CS department's instructional Unix/Linux
machines. Please see the instructions below for logging in and transferring files.
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2. All assignments in this course will be graded on CS departmental machines (e.g., royal01.cs.wisc.edu) running Linux Operating System. It is your responsibility to make sure that your code
runs on these machines correctly.
General Advice
1. If you are not using the CS departmental machines with Linux Operating System and would like to
code using your laptop then:
2. Please DON’T use an Integrated Development Environment (IDE) for learning to code in C. It will
hide many of the low-level details from you. You can become a good C programmer only if you
understand all these low-level details.
3. Avoid using Windows Operating System for writing C code since the compiler that we’ll use for
grading your assignments is gcc (GNU C Compiler) which is a Unix/Linux based C compiler.
4. If you still insist on using a computer which already has a Windows OS, then it's best to have a
virtual machine (VMware or Virtualbox) to run a Linux OS. You’ll also need a compiler like MinGW or
Cygwin (which contains tools like gcc) installed on your Windows machine. To be honest connecting
to the lab Linux machines is easier than getting those software packages installed correctly.
Questions
1. If you have a question, please consider these options in order.
2. Post your question on Piazza and make it public for general questions. Feel free to post problemsolving strategies, but do not post your code publicly.
3. If you need to post your code, then make the post private. We will in general not help debug your
code for syntax errors. We will however explain cryptic compiler error messages. Please post both
the code segment generating the error and a screenshot of the cryptic error message.
4. Email your TA. See the Office/Lab Hours page to find the best TA to connect with. This will help us
balance the load of questions and prevent Abby (who is alphabetically first) from being overwhelmed.
Debugging advice
1. Write your code in very small sections at a time and verify that it compiles before continuing.
2. Fix the compiler error messages from the top down. The first error may cause other compiler error
messages to generate from correct code later in your file. So, scroll up and address the top error
message first.
3. Ask questions about cryptic error messages. Post a screenshot of the error message on Piazza as a
public post if you do not need to share any code. Post privately if you do need to share your code.
Part 1: Logging into a CSL Machine
The first challenge is simple: being able to use one of the Linux machines made available by the CSL
(Computer Systems Lab) here at Wisconsin. The lab provides several different Linux systems for you to
use. We will be grading all projects on the CSL machines. Note that different operating systems will
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produce different output and different versions of the compiler (or selecting different compiler options)
may produce different output.
To log in, you must know your CS login which the Lab should have mailed to you. Contact them
at lab@cs.wisc.edu (mailto:lab@cs.wisc.edu) if you don't have one yet. If you are new to Wisconsin or
your account has expired, please activate your account. (https://csl.cs.wisc.edu/docs/csl/2012-09-04-
about-your-instructional-account/)
Once you know what your login is, you must pick a machine and use SSH to log in
(https://csl.cs.wisc.edu/docs/csl/2020-04-20-linux-rdp/) . The set of machines available can be found
at Instructional Linux Computers (https://csl.cs.wisc.edu/docs/csl/2012-08-16-instructional-facilities/)
If you are using a Mac or Linux machine, you can log in to one of these machines via ssh
(https://linux.die.net/man/1/ssh) by typing, at a command shell prompt, like this:
prompt ssh username@emperor-03.cs.wisc.edu
My username is doescher, so I would type:
prompt ssh doescher@emperor-03.cs.wisc.edu
Note that we use prompt to indicate what the shell shows you when asking for you to type a command;
undoubtedly, it will say something different than prompt and in fact the prompt is customizable.
It may seem kind of arbitrary to pick a particular machine, instead of (say) an unused or lightly used
machine. To have the CSL pick a machine for you, log into any one of the following: bestlinux.cs.wisc.edu. In other words, just replace emperor-03.cs.wisc.edu in the ssh line above
with best-emperor.cs.wisc.edu instead.
If you are using a Windows machine, you'll probably need to use Putty
(https://www.chiark.greenend.org.uk/~sgtatham/putty/latest.html) or another ssh client to log into the CSL
machines. See Connecting to Linux computers via SSH (https://csl.cs.wisc.edu/services/remoteaccess/connect-linux-ssh) for more options.
Part 2: The Shell
Now, you need to start getting familiar with the command shell you are using. Most of you are probably
using bash. However, you are free to use any shell you like, such as tcsh, zsh, ksh, etc. The important
thing: pick one, read about it, and learn how to use it. There are many online tutorials for shells, and the
best way to learn is to just spend some time practicing.
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One thing you'll need to know is how to move around the file system hierarchy. A Unix file system is just
what CS types call a tree, which has a single root and many children. At the root is a directory (or folder)
called the root directory. In Unix, we refer to the root as / (a forward slash). All other files and
directories (folders) are located somewhere in that tree.
When you log in to one of those Linux machines, you'll be placed into what is called your home
directory. To see what directory that is, type:
prompt pwd
The pwd command Prints the Working Directory, which should be something like this:
/u/d/o/doescher
This entity is called a pathname and it should be interpreted as follows. In the root directory (/), there is
another directory called u (I think this is short for users); in that directory, there is another directory
called d (my username begins with d); in that one, there is another directory called o (second letter of
my username), etc., on down to the last directory called doescher. The symbol / (in addition to being the
name of the root directory) is used as a separator in the path; in other words, it separates each directory
(or file) name from the others in the path. Note: Windows machines use the name of the drive as the root
(i.e. c:\) and the backslash \ as the separator. This difference is one of the major reasons that if you write
code on a Windows machine it may fail when we grade it on the Linux machines.
Now, let's do some simple shell stuff just to warm up. First, check out the files and directories in your
home directory. To do this, you will run a program called ls which lists files and directories.
prompt ls
You should see some interesting output there, including some directories
(like private/ and public/ among others) and perhaps a few files.
Let’s go create a directory to do the work for Project 1 in to keep things organized. First, let’s move into
the private directory. To do this we will run a program called cd which changes the active directory and
moves one level deeper into the tree
prompt cd private
Now try pwd again and verify that your Working Directory ends in private.
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/u/d/o/username/private
Three special directories include .. (2 dots), . (1 dot), and ~ (tilde)
cd ..
This will take you up one directory in the tree. You should end up back at /u/d/o/username if you do this.
cd .
The single dot . represents the current directory. This command takes you to the directory you are
currently in.
cd ~
takes you back to your home directory. Your starting location when you first logged in.
Let’s move back into private and then create a new directory for CS354
mkdir CS354
The mkdir program will create a new directory called CS354. Note do not use spaces in directory or file
names. (Windows will allow this if you enclose the directory name in quotation marks – but in general
using spaces even on Windows is not a good practice)
Move into this new CS354 directory. Create another new directory for Project1 and move into that
directory.
The next command we’ll learn is echo. This command simply outputs whatever text you pass as an
argument. For example:
prompt echo Hello World
just displays the text Hello World on the screen.
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Not super useful by itself but when combined with the file redirection operator can be quite useful.
Type the following at the command prompt:
prompt echo Hello World file.txt
The file redirection operator will write the contents of anything that was supposed to be printed on the
screen to a file. Note this will destroy the contents of whatever was already in this file and replace
them. To append use the command instead.
To check if your file exists now, type:
prompt cat file.txt
Hello World
If you did it correctly, you should see the text "Hello World" as shown above.
If you don't want that file around, use the file deleting command rm to remove it:
prompt rm file.txt
However, please be VERY careful with this command. It can delete your files(!). There are many stories
about accidental deletes of huge amounts of information; here is a story about how Pixar almost
deleted Toy Story 2 (https://www.youtube.com/watch?v=8dhp_20j0Ys) .
Part 3: File transfer
Download the file Number_Translation_Template.c from canvas to the computer you are using. File
links for all projects will be at the top.
Open a terminal and navigate to the directory where you saved this file.
To copy the file to the CSL machines we’ll use a program called scp which is short for secure copy. On
Windows this program comes packaged with Putty and is called pscp (short for Putty Secure Copy)
provide the following arguments to scp:
prompt scp Number_Translation_Template.c username@best-linux.cs.wisc.edu:private/CS354/Project1/Number_Trans
lation_Template.c
or on Windows:
prompt pscp Number_Translation_Template.c username@best-linux.cs.wisc.edu:private/CS354/Project1/Number_Tran
slation_Template.c
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You should be prompted for you password and see a message indicating that the file transfer was
successful.
Go back to the CSL Linux terminal and verify the file was transferred correctly with ls.
Next, let’s rename this template file. We have two choices here: cp (short for copy) and mv (short for
move). Copy will retain the original file and mv will delete the original file. Both programs take two
arguments: the first is the filename of the file to be copied and the second is the new filename.
prompt cp Number_Translation_Template.c Number_Translation.c
prompt mv Number_Translation_Template.c Number_Translation.c
My goal by providing files with the word Template is that students do not turn in the original template
instead of the file they did their work in. This is the number 1 mistake that results in getting a zero on an
assignment. Don’t worry if you make this mistake it happens to several students every semester. We
will work with you if this happens so you can submit your real assignment.
From here on do all your work in the Number_Translation.c file.
Note: If you learned another technique for transferring files to the CSL machines in another class you
are welcome to use that strategy instead.
Part 4: Converting Binary and Hexadecimal to Decimal.
The primary component of this homework assignment will be to convert binary and hexadecimal strings
to integers and decimal numbers into binary and hexadecimal representations (as strings of characters).
Compile and run the code with:
prompt gcc -o Number_Translation Number_Translation.c -m32 -Wall
prompt ./Number_Translation
Don't type the word "prompt ". The terminal gives you a prompt where it accepts text entry. Terminal
prompts are highly customizable - my prompt tells me which machine I'm logged into but frequently they
also print your current directory.
Main: The main function in the template file displays a menu of options and then asks for user input.
There is no need to change main. Each option calls a function to request user input. Then it calls a
function to convert the numbers, and finally prints the results.
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Input: The GetHexFromUser function has been completed for you, but you will need to write the other
two: GetBinaryFromUser and GetDecimalFromUser. Note, the format string specifier for an unsigned int
is %u.
Conversion Functions: The four conversion functions are all void functions meaning that they do not
return a result. Instead, they take pointers to the variables from main and modify those arrays or
variables. The first parameter is the input data that is converted to the type of the second parameter.
Please use only upper case letters in the hex output.
Output: Printing the results has been taken care of for you in main. There is no need to change main.
You are highly encouraged to write print statements as you write your code. Printing after every line (or
every few lines) of code to verify that the line you just wrote is actually doing what you think it should be
is known as scaffolding. Just remember to remove the scaffolding before you turn in your work.
Now, look at the code in your favorite text editor. Some popular text editors used in the Unix/Linux OS
environment are:
vim
emacs
Learning emacs or vim will be unpleasant at first but a little practice will pay off quite a bit in the long
term, especially if you plan on taking advanced systems courses at UW.
Use the text editor of your choice to open the file Number_Translation.c.
At the top, you will see a section for compiler directives which so far have only a single include
statement and some defines. The defines declare numerical constants that we will use for array lengths.
Using this will prevent us from needing to hardcode array lengths in the rest of the program.
Below that are the function prototypes or declarations. These are needed because the C compiler
needs to check the correctness of function calls as it reads the code. It needs to know the expected
types of input and output for each function. If you add any helper functions while doing the assignment
you will need to add prototypes for those functions here. Do not change the prototypes for the functions
already here.
The main function comes next. There is no need to change main for this assignment. Feel free to add
additional lines to help debug your functions as needed but remove them before you submit your
assignment.
Following main are the functions you will need to write for this assignment.
GetBinaryFromUser(), GetHexFromUser(), GetDecimalFromUser()
These functions prompt the user to enter a positive number. Then use scanf
(https://www.tutorialspoint.com/c_standard_library/c_function_scanf.htm) to get the retrieve the number
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entered by the user. Note that GetHexFromUser has been completed for you. The input may use either
upper case or lower case letters. Conversion to upper case is taken care of in GetHexFromUser.
ConvertBinaryToDecimal(), ConvertHexToDecimal(), ConvertDecimalToBinary(),
ConvertDecimalToHex()
These functions have two parameters, the first parameter is the input number and the second parameter
is the output result. Arrays are passed with pointer notation, input integers are passed as call by value
to make a copy of the number, and output integers are passed as pointers so they can modify the
variable in main. Remember that you can use pointers just like arrays. If you are new to pointers you
can think of this as a way to pass by reference, but pointers are very powerful, and you have many
options for how you may use them. Note that the hexadecimal numbers should contain the leading 0X.
Do not include leading zeros in the results. The Conversion functions are hardcoded in the template to
fill in the result with a number so you can what the format of the number should look like when they are
printed. Please use only upper case letters in the hex output.
Hint: consider that C strings are terminated by '\0'. You can take advantage of this to find the length of
the string.
Testing
Please make sure that your program prints the output exactly as the template file, because we use
automatic scripts to test your code.
To test your code we are providing sample input and output files. Using these is a two-step process.
First, you will need to run your code using input-redirection (<) to use the input file and produce output.
This output will be redirected to a file with (). Second, use diff to compare your output to the test output
provided. diff will identify lines that are different from the test_solution. If the outputs are identical then it
doesn't write anything (this is the desired result):
prompt ./Number_Translation < test_input.txt my_output.txt
prompt diff my_output.txt test_output.txt
Note this technique for testing your work will not display the input commands and so the output will look
different than if you run the code and enter the input manually from the keyboard.
Part 5: Turning in your work
From a terminal on your home computer use the following command to download your work to your
home computer:
prompt scp username@best-linux.cs.wisc.edu:private/CS354/Project1/Number_Translation.c ./Number_Translation.
c 
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Project 1
or on Windows use pscp:
prompt pscp username@best-linux.cs.wisc.edu:private/CS354/Project1/Number_Translation.c ./Number_Translatio
n.c
Note that if you open the file on your home computer and then resave it may change the line ending
symbols. Linux uses one bit pattern to represent end of line characters and Windows uses another. It
would be best to make all changes on the CSL machines.
Upload your assignment to Canvas.
Style_Guide.pdf (https://canvas.wisc.edu/courses/230411/files/18260001/download?download_frd=1)
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Total Points: 50
Criteria Ratings Pts
10 pts
10 pts
10 pts
10 pts
10 pts
1. Compilation 10 pts
Code compiles
0 pts
Code does not compile
2. Binary to
decimal
test the given
input and a
larger input
10 pts
Both
answers
correct
8 pts
Both answers correct,
output does not
match exactly
5 pts
One
correct
answer
3 pts
One correct answer,
output does not
match exactly
0 pts
Incorrect
answers
3. Hex to
decimal
test the given
input and a
larger input
10 pts
Both
answers
correct
8 pts
Both answers correct,
output does not
match exactly
5 pts
One
correct
answer
3 pts
One correct answer,
output does not
match exactly
0 pts
Incorrect
answers
4. Decimal to
binary
test the given
input and a
larger input
10 pts
Both
answers
correct
8 pts
Both answers correct,
output does not
match exactly
5 pts
One
correct
answer
3 pts
One correct answer,
output does not
match exactly
0 pts
Incorrect
answers
5. Decimal to
hex
test the given
input and a
larger input
10 pts
Both
answers
correct
8 pts
Both answers correct,
output does not
match exactly
5 pts
One
correct
answer
3 pts
One correct answer,
output does not
match exactly
0 pts
Incorrect
answers