Lab 7

Logistics

  • Due: Monday, May 1st AoE.
  • Submission instructions: ensure that you have the source code you want us to grade in your ~/csci112_spring2023/labs/lab7 directory, and that the snapshot (commit) of your repository containing the version of that file you want us to grade has been committed and tagged as lab7. See the git lecture and classwork 4 for more details.
  • Note that grading will be done on D2L, so you can see comments and a detailed breakdown of your score there, but you do not need to submit anything there.
  • Deadline reminder: for this assignment, no lates will be accepted.

Learning outcomes

  • Practice using pointers to create a linked list
  • Practice using malloc and free to dynamically allocate and deallocate memory.

Assignment

Write a struct called an Exhibit that holds information about an exhibit in a zoo, and can also be used as a node in a linked list containing an arbitrary number of Exhibit nodes stored on the heap. Then, write functions to create and return a new Exhibit, add to the list at the front, delete a given exhibit from the list, and print the whole list. In main, use your functions to create a list of exhibits, remove some, and add some more. At the end of your main function, you should free the entire list. If you would like, you can use a pre-written main and header file containing the function prototypes and Exhibit definition, found in /public/labs/lab7 in the files lab7.c and lab7.h, respectively. In this case, you just need to provide the funcs.c file (and a Makefile). If you would like to write your own main and your own header file, that is also fine.

Program specification

Your program must include the following structs and functions with exactly the specified inputs and return types. These are already in the /public/labs/lab7/lab7.h file if you want to use it.

  • Struct Exhibit with fields for the name of the exhibit and the next exhibit (a pointer to an Exhibit).
  • Function print_exhibits that takes in a pointer to an Exhibit and prints out the entire list starting from that node.
  • Function create_new_exhibit which takes in an exhibit name and returns a pointer to an exhibit with that name. It must use malloc to allocate space for the new exhibit on the heap.
  • Function insert_exhibit_at_front which takes in a double pointer to an Exhibit (for the start of the list) and a pointer to the exhibit to be added, and adds the new exhibit to the front.
  • Function delete_exhibit which takes in a double pointer to an Exhibit (for the start of the list) and an exhibit name and removes an exhibit with that name from the list. It must use free to free the memory on the heap for the deleted node.
  • Function delete_all which takes in a double pointer to an Exhibit (for the start of the list) and uses free to free the memory for the entire list.

Hints

  • Follow the implementations of print, insert at front, delete, and delete all for linked lists from class.
  • If you aren’t sure how to implement one of the functions, draw a picture of what it needs to do before writing code.
  • You can check for memory leaks using valgrind. For example, run
    valgrind --leak-check=full \
       --show-leak-kinds=all \
       --track-origins=yes \
       --verbose \
       --log-file=valgrind-out.txt \
       ./lab7 < /public/labs/lab7/test1.txt

    and check the valgrind-out.txt file. At the bottom of the file you will find information about whether you have memory leaks. If you do, check that you are freeing all of the memory you allocate! See this stack overflow post if you would like to know more about valgrind.

Sample run

You don’t need to match the output format.

[p19t655@csci112 lab7]$ make
gcc -c lab7.c -Wall
gcc -c funcs.c -Wall
gcc lab7.o funcs.o -o lab7
[p19t655@csci112 lab7]$ ./lab7
How many exhibits would you like to add? > 3
Enter exhibit name > Seashore
Enter exhibit name > Riverside
Enter exhibit name > Lakeshore

Lakeshore->Riverside->Seashore->
How many exhibits would you like to delete? > 1
Enter exhibit name > Riverside

Lakeshore->Seashore->
How many exhibits would you like to add? > 1
Enter exhibit name > Jungle

Jungle->Lakeshore->Seashore->

Test data

There are test files and sample outputs in the /public/labs/lab7 directory.

Grading - 100 points

If your code does not compile, has a runtime error on the sample input, or uses global variables (variables declared outside of main), you get an automatic 0.

  • 10 points: struct Exhibit is implemented as described
  • 10 points: function print_exhibits is implemented as described
  • 5 points: function create_new_exhibit is implemented as described (excluding malloc)
  • 5 points: function create_new_exhibit correctly uses malloc to allocate memory on the heap
  • 10 points: function insert_exhibit_at_front is implemented as described
  • 10 points: function delete_exhibit is implemented as described (excluding free)
  • 5 points: function delete_exhibit correctly uses free to free the memory allocated for the deleted node
  • 5 points: function delete_all successfully deletes all nodes from the list
  • 5 points: function delete_all correctly uses free to free the memory allocated for the all remaining nodes and is called at the end of main
  • 5 points: program prompts the user as in the sample
  • 5 points: uses at least one header file and at least two C source code files
  • 5 points: provides a Makefile that correctly encodes the dependencies between the files and can successfully compile it
  • 5 points: source code is in a commit with tag lab7.
  • 5 points: source code is in csci112_spring2023/labs/lab7 directory.

Go beyond

  • Implement your print_exhibits and delete_all functions recursively.

Grading turnaround

This lab will be graded within one week of its due date.

Starter code

If you are unable to access the server, here are the two starter files.