CS 305: HW 1

CS 305: HW 1

Name your writeup username _hw1.txt where username is your UP login.
This assignment is meant to give you practice with C programming and to compare/
contrast a C implementation with a Java implementation (namely, HW 0). READ
INSTRUCTIONS CAREFULLY, THERE ARE SOME DIFFERENCES BETWEEN HW0 AND
HW1.
This assignment should be completed individually. Advice: start as soon as the
homework assignment is posted, so you have plenty of time to get the code to
compile, have time to test, have time to debug, have time to re-test, and have time
to complete the summary report.
Specification
You will implement a C version of HW0 (items and inventory that keeps tracks of
items) for this assignment.
The final code should include the following five files:
 item.h – defines the inventory struct and the function prototypes that
operate on the items (needs to be completed, included in starter code)
 inventory.h – defines the inventory struct and the function prototypes that
operate on the inventory data structures (needs to be completed, included in
starter code)
 main.c – test program (done, included in starter code)
 inventory.c – implements the functions (you must create the file)
o create_inventory
o add_item
o sold item
o calc_min_price
o calc_max_price
o calc_inv_value
o delete_item
o print_inventory
o free_inventory
 item.c – implements the functions (you must create the file)
o create_item
o print
To compile a C program that has multiple files:
gcc -o main inventory.c item.c main.c
To run it:
main
(or)
./main
Practical Notes:
i. Comment out everything in the main.c:run_test(void) and start writing your code
with the first line only that creates inventory. This way you only test tiny coding
increments
inventory* rei = create_inventory(-3);
ii. After the above works, implement the free_inventory function and uncomment
the very last line:
free_inventory(rei);
iii. Run your code (executable) through valgrind and make sure you deallocated
all the memory you allocated to run the program. The easiest way to check is to run
your program inside of a valgrind as such:
valgrind ./main
you will see some additional printout on the screen before the code executes, then
the printout of your code, and at the end you should see the following if you
deallocated all memory.
ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
iv. incrementally implement the rest of your code and incrementally test it by
uncommenting the lines in the run_test function.
1. Open item.h. Below are the struct members. Complete the struct definition
item (use typedef so the type item can be used in your code).
2. Open inventory.h. Below are the struct members for inventory. Complete the
struct definition for inventory (use typedef so the type inventory can be used in
your code). Note that items is a pointer to item (aka, an array of item objects).
item
------------------------------
price: double
name : char[MAX_NAME_LENGTH + 1]
id_number : int
inventory
---------------------------
items : item *
stock: int *
num_items : int
max_items : int
3. Open main.c to see how the code can be used and tested. Similar to HW0, the
run_test function creates two inventories and adds and deletes items and prints
the inventory items. The printouts include item’s price, name, id, stock and the
additional store’s inventory statistics: total inventory value, cheapest and most
expensive item in the inventory.
4. Create a new file called item.c. At the top, put a useful comment that at least
includes your name. Then, include <stdio.h, “item.h”, and “inventory.h”. If
you need to see a syntax example of how to include header files, see main.c.
Implement the following functions (can copy and paste function prototypes from
item.h):
 create_item
o declare a item object
o set parameters price, name and id_number to the item’s struct
members that make sense; negative item ID numbers and negative
price do not make sense, so you should set default values that do
make sense
o set the first MAX_NAME_LENGTH chars in the parameter name to the item
object name and ensure that the name of the item is exactly
MAX_NAME_LENGTH chars long
 For example, if MAX_NAME_LENGTH is 10 and the name passed in
as the parameter is “Warm Hat”, then the time’s name should be
“Warm Hat “ (with 2 extra spaces to make the name exactly 10
characters long).
 For example, if the item name passed in is “Warm Hat The
Warmest ”, then the stored name should be truncated to “Warm
Hat T”.
 This ensures that the printing of the inventory has a fixed width
field for the name, so the printing of the items lines up nicely.
o set the name at position MAX_NAME_LENGTH to ‘\0’ (the null-terminating
character) to end the string correctly in C
o return the item object
 print (routine implemented in item code)
o prints the item passed in as a parameter as follows:
Item 10.25 WarmFingers 1 10
(see example output for format; it should be item’s price, name, ID and
stock count with tabs in between.
Hint: you can use %.2f in C to state that you want fixed (2) digits of
mantissa showing.
5. Create a new file called inventory.c. At the top, put a useful comment that at
least includes your name. Then, include <stdio.h, <stdlib.h, “item.h”, and
“inventory.h”.
Implement the following functions (can copy and paste function prototypes from
inventory.h):
 create_inventory
o create an inventory pointer variable items and allocate memory for
the size of the inventory object
o set num_items to 0
o set max_items to max_it (if positive)
o set max_items to 10 (if max_it <= 0)
o allocate memory for the array of max_items of item objects. Assign
the items pointer to the allocated memory.
o create an int pointer stock and allocate memory for the stock array
of ints max_items large.
o return the pointer to the inventory
o (note: since the object is a pointer to a inventory, use - instead of .
to access data members)
 add_item
o if the number of items num_items in the inventory is = max_items,
then print “Cannot add another item to inventory. Max
inventory size exceeded”. Return -1.
o Else, iff the item it’s id_number does not exist in the inventory, store
the item it in position num_items of the array items and update
num_items of the inventory by adding one. Return 0.
o if the item already exists, don’t add it, print error: “Cannot add item
to inventory. Duplicate item ID number”
 sold_item
o if item’s id item_id is found in the store’s inventory, decrement its
stock count by one and print message that the item was sold
o if the item is found, but the stock count is 0, print error: “Cannot sell
item that has 0 inventory count” and return.
o If the item is not found in the inventory, print error: “Cannot sell
item that is not in the inventory”
 delete_item
o if the num_items in the inventory is <= 0, print error “Item number
___ not found. Store is empty.” Return -1.
o Look for the first occurrence of the item_num in the inventory that
matches the item’s id_number. If such an item is found, delete it and
shift all items in the inventory after it (on the right) by one position to
the left. Update the num_items to be one fewer and return 0. If such an
item is not found, print error “Item w/ number ___ not found in
the inventory.” and return -1.
o Note there should not be more than one instance of an item in the
inventory. See add_item specifications.
 calc_[min, max]_price
o find the item with the [lowest, highest] price in the store’s inventory
o return the value found
 calc_inv_value
o calculates the overall value of the inventory as a sum of (item's
price * the stock) for all items in the inventory
 print_inventory
o prints the inventory as item, price, name, id, and stock for the
store’s inventory passed in as inventory* inv. Use the print
function for item objects.
o after printing the store’s items, print the inventory’s value and the
price of cheapest and most expensive price in the inventory.
 free_inventory
o should take a pointer to a inventory as a parameter
o free the store’s → items
o free the store’s → stock
o free the inventory object
Error-checking
All methods should do proper error-checking of the parameters. If a parameter
value does not make sense (for example, a negative price or a negative id), then
the code should set an appropriate value such as 0 or 1.
Documentation
The code should be well-commented, well indented, and include enough whitespace
to be readable. Each of the .c files should have a block comment at the top that
includes information about the author and included code.
You may want to review the questions on the summary report before you start
coding. One question asks you to list at least 2 compiler error messages that you
get, so you may want to log those while you are working on the assignment.
Example Output
See sample_output.txt on moodle.
Additional Enrichment
If you have time, feel free to add the components to your program. But, keep the
original code saved!!! You can submit multiple folders of code. If you do any
enrichment, please put the original code files in a folder called hw1 and put the
enriched program in a folder called hw1option. Then zip both folders into a single
file.
Please document the additional features in your code and your written summary.
This is not extra credit, but a chance for you to do some exploration.
 Add more attributes to items, such as “type” (grocery, garden, home,
jewelry, etc.). You may need to create new run_test functions to account for
these new attributes.
 If you have items with attributes, print the inventory items according to
category or out of stock instead of the order that the items are stored in the
inventory.
 Add other features to the inventory to make it more closely resemble a real
inventory such as dates, store location, etc.
Logistics
1. Download the starter code located on Moodle. You may use any IDE or just a
text editor (emacs or another one) to write your code. However, your code
must compile with gcc on the Shiley’s Ubuntu VDI machine.
2. When you are finished and ready to submit:
1. Create a new folder called username_HW1.
1. (For example, Martin’s would be cenek_HW1.)
2. Copy the 2 header files and 3 code files into the folder.
3. Copy your username_hw1.txt file into this folder.
4. Copy your sample_output.txt file into this folder.
5. Zip the folder by right-clicking and Send To-Compressed Folder (on
Windows). There should also be a zip utility on Mac or Linux.
3. What to turn in: Submit your username_HW1.zip file to Moodle before the
due date and time. After logging into learning.up.edu, navigate to CS 305. 
You will find a link to submit this file. You do not need to print anything for
this homework submission.
Grading Guidelines (total of 20 points)
Your files will be graded in three separate categories:
 (5 points) Code Quality: Design, commenting, whitespace, readability, proper
indentation, consistent naming conventions
 (10 points) Code Operation: Does code do what is listed in the specification?
Note: code that does NOT compile will receive 0 points for code operation.
o 1 point item.h
o 1 point inventory.h
o 2 points item.c (1 pt per function)
o 6 points inventory.c (1 pt per function, 2 points for delete_item)
 (5 points) Summary report: Completeness, correctness, and clarity
HW 1 Report Guidelines and Format – use the template provided below.
Include the questions in your write-up.
Name:
CS 305 HW 1 Report
1. Questions (include these in your write-up):
1a. (.5 point) If your program does not meet the specifications, please note the
differences and anything that is not working correctly. If it works, write “Meets all
specifications.”
1b. (.5 point) Include the output file called sample_output.txt in your zip file from
executing your program with the original run_test() function.
You can create an output file of what is printed to the screen with the command line
command (assuming your executable is called myinventory):
./myinventory sample_output.txt
1c. (1 point) Show test cases (such as run_test2, run_test3, etc.) that demonstrate
how you conducted other test cases (such as negative number input error-handing,
removing items from an empty inventory, creating items with names longer than 30
characters, etc.). For this question, you should label the test case (what condition
you are testing), provide the test code, and provide the program output.
2. The functions that operate on inventories take the inventory object as a pointer
to a inventory when passed as a parameter. This is because the inventory object is
modified by some of the functions and we want those modifications to remain in
place after the function is finished executing (this is sometimes referred to as “side
effecting”). Note that in Java, all object types are passed by reference (pointer to
the object), so the object state can be modified by methods. However, in C, you
have the choice to pass objects directly (no pointer) or to pass objects via pointers.
Passing objects directly without pointers means that any modifications to the object
are lost when the function is done executing.
2a. Why are the functions that operate on item objects defined without using
pointers to the items as parameters?
2b. Why are the functions that operate on inventory objects defined using pointers
to the inventory objects as parameters? Which methods change the contents of the
inventory struct?
3a. In the run_test function, you will see comments about drawing picture 1 and
picture 2. Draw the picture of the rei object at the point where the comment point
to draw picture 1 is located. Use arrows to indicate pointers. The picture should
include all components of the rei object.
3b. Draw the picture of rei at the point of execution where draw picture 2 is located
in run_test.
4a. Describe a difference between C and Java that you have observed by
completing HW 0 and HW 1. (I already described that Java uses pass by reference
for all object types and C uses pass by value, so that difference cannot be used
here.)
4b. Describe an aspect that is the same in C and Java based on HW 0 and HW 1.
5a. What compile error messages did you receive when working on this
assignment? For at least 2 compiler error messages you received, write the
compiler error message, describe what the message means, and describe how you
resolved it in a table below.
Compiler error message What it means How I resolved it
5b. How much time did you spend in total on this homework assignment (including
the report)? Was this more or less time than you spent on HW 0? (Learning to use a
new programming language takes time, so it is not surprising if HW 1 took
considerably more time than HW0.)
Appendix A: (copy this statement if it applies to you) I verify that the code
and this write-up were authored by me. I have documented the help I have received
in comments in the code files.
Appendix B: Copy and paste your item.h, item.c, inventory.h, and inventory.c code
files here (use Courier New 8pt font so the characters line up correctly)