TC Validator (C++)

A small, production-style C++ console tool that validates credit card numbers with the Luhn checksum and performs card brand detection (Visa, MasterCard, AmEx, Discover).

Project layout

• include/CreditCard.h — CreditCard class (encapsulation, operators, brand detection, validation)
• src/CreditCard.cpp — implementation (Luhn + prefix/range rules)
• src/main.cpp — CLI: reads an input file and writes results to an output file
• tests/test_creditcard.cpp — lightweight unit tests (no external framework)
• cards.txt — sample input (one number per line)

The original school-style implementation in Credit.cpp / Credit.h and Lab4C++.cpp is kept for reference; the portfolio-ready version is the CMake + src/ + include/ code.

Build

Recommended: CMake (cross-platform)

cmake -S . -B build
cmake --build build
ctest --test-dir build --output-on-failure

If cmake is not installed, install it via your platform package manager (e.g., Homebrew on macOS: brew install cmake).

Manual build (macOS/Linux)

clang++ -std=c++20 -O2 -Iinclude src/main.cpp src/CreditCard.cpp -o tc_validator
clang++ -std=c++20 -O2 -Iinclude tests/test_creditcard.cpp src/CreditCard.cpp -o tc_validator_tests

Usage

The CLI reads an input file and writes results to an output file.

./tc_validator cards.txt validation_results.txt

Output format (one line per card):

4111111111111111 : Visa : valid
1234567890123456 : Unknown : invalid

Notes:

• Inputs may include spaces or hyphens (e.g., 5555 5555 5555 4444, 6011-1111-1111-1117).
• Invalid characters throw a CreditCard::Error and are reported as invalid_input in the output file.

Architecture notes

CreditCard stores the original input and a normalized digits-only representation.

• CreditCard::brand() returns std::optional<Brand> (unknown prefix → std::nullopt).
• CreditCard::isValid() checks length (13–16), known brand prefix, then runs Luhn.
• Rule of Three is demonstrated via an owned char* buffer with deep copy semantics.

License

MIT