INTRO TO C HW1 SELECT-COLUMN

Starter code: select-column-package.tar

Upload solutions via Gradescope as: select-column.c

Goals

Get started with some of the fundamentals of C programming
Get used to using some simple program testing automation in the form of a Makefile and sample test data
Get experience reading man pages

Assessment

To demonstrate proficiency, your submission needs to:

Pass the autograder tests
Be somewhat well-styled

To demonstrate mastery, your submission needs to:

Demonstrate proficiency
Be quite well-styled, particularly well-chosen variable names, naming all magic numbers, and good indentation
Have a well-chosen algorithm (i.e. don’t over-complicate this task!)
Have thorough error-handling

Logistics

This is an individual assignment, so you should write all the code individually, though you can get help, as detailed in the collaboration document.

This assignment is due Friday March 29th at 10pm. As with all assignments, you will have the opportunity to revise this submission based on feedback.

GETTING STARTED WITH C

This term, nearly all of your work will involve the C programming language either directly or indirectly. As we get started with C, I am assuming that you have a working knowledge of both Python and Java, to the level they are taught in CS 111 and 201.

I also assume you will familiarize yourself with the program examples from the Samples page. You should definitely study and play with those programs, and you may feel free to plunder them for code to use in your own programs.

Your first few homework assignments will focus on a few core C concepts:

program structure: main, #include, functions, and function prototypes
input: scanf, fscanf, fgetc, and fgets
output: printf, fprintf, fputc, and fputs
essential variable types: char, int, float, long, and double
conditionals: if, else, and boolean expressions
loops: while and for
arrays
null-terminated char strings along with their associated library functions strlen, strcmp, strncpy, and strncat
command-line arguments with argc and argv
structs
pointers, including the operators *, &, and ->
memory allocation: malloc and free

CSV FILES

The input for your first program will come in the form of a comma-separated values file. CSV files give us a simple way of representing tables. Each line of text represents one row of the table, and each row is separated into columns by commas. For example, here is a simple CSV file animals.csv representing a table with a heading row followed by five data rows, with three data cells (or columns, if you prefer) per row:

Animal,leg count,eye count
dog,4,2
emu,2,2
spider,8,8
ant,6,2
sea star,5,5

The official CSV format has to worry about whether any of the data in the cells contain commas, but we’re not going to worry about that. For this assignment, you may assume that there are no commas in the data, so any comma in the CSV file marks a separation between adjacent data cells.

PROGRAMMING ASSIGNMENT #1: SELECT-COLUMN

For this assignment, you will write a C program select-column.c that takes a CSV file and a 1-based column number as command-line arguments, and prints the specified column of the file to standard output.

For example, suppose we run your program like so:

./select-column animals.csv 2

where the file animals.csv is as shown above. Then the expected output is:

leg count
4
2
8
6
5

If the specified column does not exist in a particular row of the file, print an empty line for that row.

GETTING THE STARTER PACKAGE

For many assignments this term, you’ll receive some starter code, some testing tools, or miscellaneous other materials to help you get started. These will generally be delivered to you via downloadable tar files. As noted in this handy tutorial from Indiana University, you can extract the files and folders contained in a tar file by using the command:

tar xvf whatever.tar

To get started on this first assignment:

In your VS Code terminal, run:

  wget https://anyaevostinar.github.io/classes/208-s24/select-column-package.tar

Still in your VS Code terminal, extract the select-column-package folder:
```
  tar xvf select-column-package.tar
```
This will create a folder named “select-column-package” with some stuff in it.
Read the readme.txt file and get started.

AUTOMATED TESTING

In the select-column-package.tar file linked at the top of this page, you will find:

Makefile: a file that you’ll use to compile your program and run one very simple test
readme.txt: an explanation of how to use the Makefile
some test data files

For most assignments, I will only give you very simple tests in the assignment’s starter package. The Gradescope autograder will run some more sophisticated tests to explore the boundaries of a given assignment. You are, of course, free to use the testing infrastructure from the starter package to add your own tests. Getting used to automated testing and to writing detailed tests of your own will serve you well in the long-run.

SUBMITTING YOUR WORK

upload select-column.c to Gradescope
wait for the autograder to run and feel free to resubmit if the autograder points out an issue

A LITTLE ADVICE

Think ahead of time about error handling. What could go wrong with the command-line or the input file or anything else in your program? What should your program do when those things happen? (And look at the sample programs for error handling examples!)
Think ahead of time about testing. What special cases should you test? How can you test them?
Assume that each line ends either with a newline character \n (ASCII 10) or with the end of the file. You’ll want your program to work even if the last line doesn’t end with \n.
For this program, you won’t need to read entire lines into memory. This problem is solvable just reading one character at a time using fgetc (and you shouldn’t over complicate it).
You’ll probably find the atoi function helpful, check in 2.6 of the book or do man atoi on the Terminal to learn more

HAVE FUN!

Don’t by shy about experimenting and asking lots of questions.