In this project, you will explore how characters are represented numerically in a computer, and compare the decimal, hexadecimal, octal, and binary formats for those numbers. The project will also give you additional practice with programming in C and using git. (See the Kit Help Page Working with Kit Repositories (plain text version) for reminders on using Git and Kit together.)

You should work on this project individually. You may talk to your neighbors in class, or to friends or the TAs in the Collaboration Center, but you should submit your own work. Don't forget to document any help you receive in your program.

Getting Started, Understanding the Program:

• Clone the repository for the Character Representation project. (See the PowersOfTwo Project for a reminder of how to clone a Git repository from Kit. Don't forget to rename the directory to something more meaningful, e.g., characterRepresentation or charRep.)
• Go to the new repository directory and list the files. There are several header files (*.h), several C source files (*.c), several testfiles (testfile1.txt and others), an INSTRUCTIONS.md and a README.txt file.
• Read the README.txt file to learn what the program is supposed to do. Compile and run it with each of the input testfiles, and compare the results to what the README.txt file claimed. You will probably want to cat each input file before running the program on that file, so that the output will make more sense.

      cat testfile1.txt
      ./a.out testfile1.txt
  

• Read the top-of-file comments in characterReps.c to see what it does.
• Then read through the code for the main function. It is quite a bit longer and more complex than the main function in the PowersOfTwo Project, although the changes you will be making are quite simple.
  • Find the statement that creates the buffer variable. This is an array of characters that has to be big enough to handle however many characters are on a single line of the input. Since we can't know in advance how big that needs to be, we use the value BUFSIZ, which is defined in stdio.h as the maximum number of characters your computer can handle on a single line.
  • After the variable declarations, the first two "stanzas" of code look to see if any input file was provided on the command line. If not, the program will expect input from the keyboard (possibly multiple lines), so it puts out a message telling the user how to mark the end of the input. The fptr variable is a file pointer to either the input file or standard input (the keyboard) — in other words, where the program will get the input.
  • Then the program enters a while loop, reading one line in from the input each time through the loop. The call to fgets tells it to read at most BUFSIZ characters from the file specified by fptr and put those characters in the buffer character array. (The loop ends when fgets returns NULL because it hit the end of the file.) The program then gets the length of the line and prints out the first character in several different formats.

    ⇒ What it should be doing is printing out the value of every character in the line in several different formats, not just the first character.

    Then it prints the value of the final null byte at the end of the line in several formats, followed by an extra newline for readability.
  • At the end of the program, it closes the file it was reading from.

Modification #1: Report on All Characters in a Line:

• Edit the characterReps.c source file to make the program print all the characters in the line in all formats, not just the first character in the line. As specified in the syllabus, your program should adhere to the Kalamazoo College CS Program Style Guide and Documentation Standards, including use of the Braces Line Up style pattern.
• Test your program. You can create your own test files, if you want, in addition to the two that are provided.
• Edit the internal comments (including top-of-file comments) and external documentation (README.txt) to better reflect the current functionality of the program. (The purpose of external documentation is to provide enough information for a new user to know how (and why) to use your program.)
• Upload the program to Kit by doing a git status, git add, git status, git commit -m 'short descriptive message', and git push.

Modification #2: Add Binary Format:

• Copy the printIntAsBinary.c file from your PowersOfTwo project to this directory.
• Modify your main function to print each character in binary format as well (decimal, hex, octal, and binary). (You can look at your PowersOfTwo code for a reminder of how to do this.) Test and debug as necessary.
• Edit the internal comments (including top-of-file comments) and external documentation (README.txt) to reflect the current state of the program.
• Upload the program to Kit, using git status/add/commit/push.

Remember, you can complete the edit/add/commit/push cycle repeatedly. In fact, pushing versions of your project while it is still under construction is a way to create backups of your work as you go.

Turn In the Project:

• When you're done, click on the Turn In button in Kit to signal that your project is ready to grade. (You can still edit/commit/push new changes after clicking on the Turn In button if you think of something you forgot earlier, but if the project has already been graded you will need to submit a Regrade Request in Kit to indicate that the project has been updated. Whether regrade requests are granted depends on the grader's workload and the significance of the project modifications.)