C Fundamentals: Core CS Concepts by Hatim El HassakC Fundamentals: Core CS Concepts by Hatim El Hassak

C Fundamentals: Core CS Concepts

Hatim El Hassak

Completed work

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Linux

macOS

Make

Cybersecurity

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Completed work

Posted Feb 13, 2026

Demonstrated core CS concepts with C implementations.

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C Fundamentals

A collection of fundamental computer science implementations in C.

This repository demonstrates core CS concepts including algorithms, data structures, and systems programming with clean, well-documented code.

📁 Structure

c-fundamentals/
├── algorithms/
│   ├── sorting/          # Selection sort implementation
│   └── encryption/       # Caesar cipher with frequency analysis
├── systems/
│   └── sysinfo/          # Cross-platform system information
├── Makefile              # Unified build system
└── README.md

🛠️ Building

# Build all modules
make all

# Build specific module
make sorting
make encryption
make sysinfo

# Run tests
make test

# Clean build files
make clean

📦 Modules

Selection Sort (`algorithms/sorting/`)

Classic selection sort algorithm for sorting strings and integers.

# Interactive mode
./build/sorting

# With command-line arguments
./build/sorting banana apple cherry
# Output: ["apple", "banana", "cherry"]

Complexity: O(n²) time, O(1) space

Caesar Cipher (`algorithms/encryption/`)

The classic Caesar cipher with encryption, decryption, and frequency analysis cracking.

# Encrypt with shift 3
./build/caesar-cli -e 3 "Hello World"
# Output: Khoor Zruog

# Decrypt
./build/caesar-cli -d 3 "Khoor Zruog"
# Output: Hello World

# Crack (frequency analysis)
./build/caesar-cli -c "Khoor Zruog"
# Output: Guessed shift: 3
#         Decrypted: Hello World

System Info (`systems/sysinfo/`)

Cross-platform utility to display system information.

# Basic info
./build/sysinfo

# Verbose (includes CPU, memory, user info)
./build/sysinfo -v

Supported platforms: Linux, macOS, BSD

🔧 Technical Details

Standard: C11

Compiler: GCC/Clang with -Wall -Wextra -Werror

Platform: POSIX-compliant (Linux, macOS, BSD)

Build: Make

📚 Learning Goals

This project demonstrates:

Concept Implementation Algorithms Selection sort, Caesar cipher Data Structures Arrays, strings Systems Programming POSIX APIs, sysctl Build Systems Makefile with multiple targets Code Organization Header files, modular design Documentation Doxygen-style comments

🔨 Development

# Clone
git clone https://github.com/hatimhtm/c-fundamentals.git
cd c-fundamentals

# Build and test
make test

# Install (optional)
sudo make install PREFIX=/usr/local

📄 License

MIT

👤 Author

Hatim El Hassak — Full-Stack Engineer

C Fundamentals: Core CS Concepts

C Fundamentals: Core CS Concepts

C Fundamentals

📁 Structure

🛠️ Building

📦 Modules

Selection Sort (algorithms/sorting/)

Caesar Cipher (algorithms/encryption/)

System Info (systems/sysinfo/)

🔧 Technical Details

📚 Learning Goals

🔨 Development

📄 License

👤 Author

C Fundamentals

📁 Structure

🛠️ Building

📦 Modules

Selection Sort (algorithms/sorting/)

Caesar Cipher (algorithms/encryption/)

System Info (systems/sysinfo/)

🔧 Technical Details

📚 Learning Goals

🔨 Development

📄 License

👤 Author

Selection Sort (`algorithms/sorting/`)

Caesar Cipher (`algorithms/encryption/`)

System Info (`systems/sysinfo/`)

Selection Sort (`algorithms/sorting/`)

Caesar Cipher (`algorithms/encryption/`)

System Info (`systems/sysinfo/`)