Calculator CLI

A production-ready, deployable command-line calculator written in C. The application evaluates simple binary arithmetic expressions interactively or via command-line flags, with comprehensive error handling and automated tests.

Features

• Evaluate addition, subtraction, multiplication, and division.
• Interactive REPL with prompts, exit commands, and helpful error messages.
• Non-interactive --eval mode for scripting and automation.
• Configurable output precision and optional quiet mode for cleaner pipelines.
• Cross-platform friendly build using a simple Makefile.
• Automated unit tests covering parsing, computation, and error scenarios.

Requirements

• POSIX-like environment (macOS, Linux, or Windows with a POSIX toolchain).
• A C11 compatible compiler (e.g. gcc, clang).
• Standard development utilities: make, install.

Building

make build

The compiled binary is placed in build/calculator.

Testing

Run the test suite with:

make test

All tests must pass before deploying.

Usage

Start the interactive shell:

./build/calculator

Evaluate a single expression:

./build/calculator --eval "12 / 4"

Adjust the displayed precision (between 1 and 15 significant digits):

./build/calculator --precision 6 --eval "10 / 3"

Disable the interactive prompt to better support pipelines:

echo "3 + 4" | ./build/calculator --no-prompt

Show all available flags:

./build/calculator --help

Installation

Install the binary into /usr/local/bin (override PREFIX or DESTDIR as needed):

sudo make install

Uninstall:

sudo make uninstall

Deployment Checklist

1. Run make clean && make build to ensure a fresh build succeeds.
2. Run make test and confirm all tests pass.
3. Package and distribute build/calculator, or deploy via make install.
4. Provide this README to operators for runbook reference.

License

This project is provided as-is without any specific license; adapt it to your organisation's licensing requirements as needed.