Organic Foods ordering system (C++)

A business system for an organic foods operation, built in C++ specifically to exercise the language's OOP features rather than just get a working app out: inheritance and polymorphism across customer/order/supplier types, templates for reusable logic, and operator overloading where it made the domain model read more naturally.

Customer ordering, supplier and order management, and delivery workflows all ran through it, backed by the STL's vector containers for the in-memory data structures and file-based persistence so state survived between runs. Exception handling ran throughout rather than being bolted on at the end, catching the real failure modes a business system needs to survive (a bad order, a missing supplier record) instead of letting them crash the program.

It's the project where modern C++ idioms, not just the syntax, first had to hold up under a real domain instead of a toy example.