Assignment 4: Watch where you point!

Due Friday, February 14th, before midnight

The goals for this assignment are:

Use malloc and free
Work with pointer-based data structures
Use gdb and valgrind.

All programs must run without memory errors and leaks!

1. Update your repository

Do a fetch upstream to obtain the basecode for this assignment.

Using the command line

Open terminal and change your current directory to your assignment repository.
Run the command git fetch upstream
Run the command git merge upstream/main

Your repository should now contain a new folder named A04.

The fetch and merge commands update your repository with any changes from the original.

2. Magic Square

Implement a program, magic_square.c, that tests whether a given matrix is a magic square. A magic square is an N by N matrix where each row, column, and diagonal has the same sum, called the magic constant.

$ make magic_square
gcc -g magic_square.c -o magic_square
$ ./magic_square < magic1.txt
8 1 6
3 5 7
4 9 2
M is a magic square (magic constant = 15)
$ ./magic_square < magic2.txt
9 1 6
3 5 7
4 8 2
M is NOT a magic square!
$ ./magic_square < magic3.txt
1
M is a magic square (magic constant = 1)

Requirements/Hints:

Read in the matrix from stdin using scanf(" %d", &val);. The first two values are the dimensions of the matrix. All subsequent integers are the values of the matrix.
Use malloc and free to allocate a 2D array to store the inputs.

3. Sorted Snacks

Implement a program, sorted_snackbar.c, that allows users to add snacks to the snackbar and displays them in alphabetical order. Your program should have the same features as last week’s snackbar, but should use a linked list to store the snacks, rather than an array.

$ make sorted_snackbar
gcc sorted_snackbar.c -o sorted_snackbar
$ ./sorted_snackbar
Enter a number of snacks: 3
Enter a name: Slurm
Enter a cost: 1.50
Enter a quantity: 3
Enter a name: Beans
Enter a cost: 5
Enter a quantity: 1
Enter a name: Carrots
Enter a cost: 2
Enter a quantity: 10

Welcome to Sorted Sally's Snack Bar.

0) Beans                cost: $5.00     quantity: 1
1) Carrots              cost: $2.00     quantity: 10
2) Slurm                cost: $1.50     quantity: 3

Requirements/Hints:

Implement the function insert_first. This function should create a new snack struct and insert it at the beginning of the list.
Implement the function clear. This function should clear and free all items in the list.
Implement the function printList. This function should print the contents of the list.
Implement three sort functions: sortCost and sortName and sortQuantity. These functions should sort by the given attribute.

4. Submit your Work

Before submitting, check that

Your programs run on goldengate using the make command!
valgrind does not report any errors!

Push you work to github to submit your work.

$ cd A04
$ git status
$ git add *.c
$ git status
$ git commit -m "A04 complete"
$ git status
$ git push
$ git status

5. Grading Rubric

Assignment rubrics

Grades are out of 4 points.

(2 points) Magic Square
- (0.1 points) style and header comment
- (0.4 points) reads in matrix from stdin
- (0.5 points) creates/deletes 2D matrix using malloc/free
- (1.0 points) No memory errors
(2 points) Sorted Snacks
- (0.1 points) style and header comment
- (0.4 points) defines a struct correctly handles deletion and insertion to a linked list
- (0.5 points) correctly sorts and displays snacks based on name, cost, or quantity
- (1.0 points) handles file and linked list nodes correctly (no memory errors!)

Code rubrics

For full credit, your C programs must be feature-complete, robust (e.g. run without memory errors or crashing) and have good style.

Some credit lost for missing features or bugs, depending on severity of error
-5% for style errors. See the class coding style here.
-50% for memory errors
-100% for failure to checkin work to Github
-100% for failure to compile on linux using make