C++ Basics

A small C++20 learning project that verifies my local C++ toolchain and includes a command-line IPv4 subnet calculator.

This repository verifies that a modern C++ workflow works correctly with CLion, CMake, Ninja, Git and GitHub across my Intel Mac and Windows ThinkPad setup.

Purpose

This is not intended to be a large C++ application.

It is a compact baseline project for:

• verifying the local C++ toolchain
• practicing C++ fundamentals
• understanding compiled languages and build systems
• working with CMake and Ninja
• using CLion as the primary C++ IDE
• keeping IDE metadata and build output out of Git
• documenting small command-line C++ exercises
• maintaining a clean Git/GitHub workflow for C++ projects

C++ is a secondary technical skill in my current learning path. My main focus remains data and process analysis, SQL, Python, BI and Microsoft-oriented data tooling.

Tested Environment

The project is used across my current developer setup:

• iMac Retina 4K, 21.5-inch, Late 2015
• Intel x86_64
• macOS Sonoma via OpenCore Legacy Patcher
• CLion via JetBrains Toolbox
• Apple clang++ on macOS
• Lenovo ThinkPad X1 Carbon Gen 9
• Windows 11 Enterprise
• CLion on Windows
• CMake
• Ninja
• C++20
• Git / GitHub
• Claude Code as an optional project assistant in the terminal

This repository also documents that the C++20 workflow works on a legacy Intel Mac setup and on a Windows ThinkPad used as a mirrored learning and development machine.

Repository Structure

cpp-basics/
├── CMakeLists.txt
├── include/
│   └── subnet.h
├── src/
│   ├── main.cpp
│   └── subnet.cpp
├── .clang-format
├── .editorconfig
├── .gitignore
├── LICENSE
└── README.md

Local CLion / JetBrains metadata, build directories and compiled binaries are intentionally excluded from Git:

.idea/
build/
build-*/
cmake-build-*/
*.exe
*.o
*.obj
*.out
*.dSYM/
CLAUDE.md

Source Files

File	Purpose
include/subnet.h	Public declarations for the subnet calculator logic
src/main.cpp	Command-line entry point, usage text and result printing
src/subnet.cpp	IPv4 parsing, CIDR handling and subnet calculation logic

Run in CLion

Open the project in CLion and run the cpp_basics configuration.

Program arguments:

192.168.10.42/24

Expected output:

Input IP:          192.168.10.42
CIDR prefix:       /24
Subnet mask:       255.255.255.0
Wildcard mask:     0.0.0.255
Network address:   192.168.10.0
Broadcast address: 192.168.10.255
Total addresses:   256
Usable hosts:      254
First usable host: 192.168.10.1
Last usable host:  192.168.10.254
Note:              Standard subnet with network and broadcast addresses excluded.

Build from Terminal

Configure the project with CMake and Ninja:

cmake -S . -B build -G Ninja

Build the project:

cmake --build build

Run the IPv4 subnet calculator on Windows:

.\build\cpp_basics.exe 192.168.10.42/24

Run the IPv4 subnet calculator on macOS or Linux:

./build/cpp_basics 192.168.10.42/24

Depending on the local CLion/CMake generator settings, the executable may also be created inside a cmake-build-* directory.

IPv4 Subnet Calculator

The calculator accepts input in this format:

IPv4/CIDR

Examples:

192.168.10.42/24
10.0.0.5/30
0.0.0.0/0
255.255.255.255/32

The calculator prints:

• subnet mask
• wildcard mask
• network address
• broadcast address
• total address count
• usable host count
• first usable host
• last usable host
• a short note for standard, /31 and /32 subnet cases

What This Demonstrates

This repository demonstrates a working C++20 baseline setup using:

• CLion as the primary C++ IDE
• CMake as the build configuration system
• Ninja as a fast build backend
• a simple include/ and src/ project structure
• C++20 configured in CMakeLists.txt
• std::optional for validation results
• std::string_view for lightweight string handling
• std::from_chars for numeric parsing
• fixed-width integer types from <cstdint>
• IPv4 parsing and CIDR prefix handling
• subnet mask and wildcard mask calculation
• network and broadcast address calculation
• basic bitwise operations in C++
• .clang-format and .editorconfig for consistent formatting
• local build output excluded from Git
• Git and GitHub for version control

Development Workflow

Before working on the repository:

git status -sb
git pull --ff-only

After making changes:

git status -sb
git diff

Only intentional source or documentation changes should be committed.

Next Steps

Possible future additions:

• add clearer validation messages for invalid subnet input
• add basic unit tests later on
• document compiler differences between Apple clang++, GNU g++ and MSVC where relevant

Notes

This repository is intentionally small.

Its purpose is to document and verify a clean C++20 development setup before building larger C++ exercises or tools.

No IDE metadata, build output or machine-specific files are committed.