Hybrid Inventory Manager

A capstone project demonstrating hybrid C/C++ design: the data layer is written in C (structs + binary file I/O), while the menu, STL, and object-oriented wrapper are written in C++. Data persists across restarts in inventory.dat.

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Project structure

capstone/
├── include/
│   ├── inventory.h          # C struct + extern "C" function declarations
│   └── InventoryManager.h   # C++ class declaration
├── src/
│   ├── inventory.c          # C backend (fread/fwrite/fseek)
│   ├── InventoryManager.cpp # C++ wrapper with std::vector + std::sort
│   └── main.cpp             # Console menu + validated input
├── Makefile                 # Primary build system
├── CMakeLists.txt           # Alternative CMake build
└── README.md

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Build & run

Option A – Make (recommended)

make          # builds ./inventory_manager
make run      # builds and runs immediately
make clean    # removes build/ and inventory.dat

Requirements: gcc (C11) and g++ (C++17).

Option B – CMake

mkdir build && cd build
cmake ..
cmake --build .
./inventory_manager

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Menu

1) Add item
2) View item
3) Update item
4) Delete item
5) List all
6) Exit

List all shows a sort prompt: press 1 (or Enter) to sort by ID, 2 to sort by name.

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Input rules

Field	Rule
ID	Positive integer, unique
Name	Non-empty, max 39 characters
Quantity	Integer ≥ 0
Price	Float ≥ 0

Invalid input prints an error and re-asks — the program never crashes on bad input.

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Test cases

• Add 3 items, exit, restart, list all – Added items with IDs 1, 2, 3, exited, relaunched. List all showed all three items correctly, confirming binary file persistence.

• Update an item, restart, view it – Updated item 1's name to "Widget Alpha UPDATED", quantity to 99, price to $14.99. After restarting and selecting View item → ID 1, all updated values were displayed correctly.

• Duplicate ID rejection – Attempted to add a new item with ID 2 (already in use). The program printed [FAIL] Could not add item (ID may already exist) and did not modify the file.

• Delete an item; confirm it disappears from list and view – Deleted item 2 ("Gadget Beta"). Listing all showed only items 1 and 3. Attempting to view item 2 printed [FAIL] Item not found or has been deleted.

• Invalid input recovery – Entered -5 for ID, abc for quantity, and empty string for name at various prompts. The program re-prompted every time without crashing, then accepted correct values on the next attempt.

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Design notes

Concern	Language	Mechanism
File I/O	C	fread / fwrite / fseek on a binary flat file
Soft delete	C	is_deleted flag set to 1 in-place via fseek
Duplicate guard	C	get_item scan before fwrite in add_item
Listing	C++	std::vector<Item> populated from list_items()
Sorting	C++	std::sort with lambda comparators
Linkage	C++	extern "C" block in inventory.h