CLings

CLings is a small interactive tool to help you get used to reading and writing C code. It mimics the popular "Rustlings" and "Ziglings" projects. The goal is to learn C by fixing small broken programs.

📋 Prerequisites

• Rust: You need to have the Rust toolchain installed to run the clings tool. Install Rust.
• GCC: You need a C compiler (gcc) installed and available in your path.

🚀 Getting Started

1. 📦 Install Dependencies: First, make sure you have installed the Prerequisites listed above (Rust and GCC). You cannot run the tool without them.

   Ensure you have gcc installed:

   • Linux: sudo apt install build-essential
   • macOS: xcode-select --install
   • Windows: Install MinGW or use WSL.

2. 🏃 Run the Tool: From the repository root, run:

   cargo run

   This launches the interactive Terminal User Interface (TUI).

3. 🧩 Solve Exercises:

   • Navigate: Use the Up/Down arrows or j/k to select an exercise.
   • Open Editor: Press Enter or e to open the selected exercise in your default editor (configured via $EDITOR).
   • Fix the Code: Read the comments and learning goal in the file. Fix the code to make it compile and run.
   • Verify: Remove the line // I AM NOT DONE when you are finished. Save the file.
   • Watch: The TUI automatically detects file changes and re-runs verification instantly!
   • Track Progress: Successful exercises are marked with a ✓ and saved to your progress file.

4. 🏆 Challenges:

   • After every few topics, there is a challenge exercise.
   • These require you to combine multiple concepts learned so far.
   • They are slightly harder than regular exercises and may require some problem solving!

🖥️ TUI Controls

Key	Action
j / Down	Move selection down
k / Up	Move selection up
l	Expand/Collapse folder
h	Show hint (exercises only)
e / Enter	Open current exercise in Editor
q / Esc	Quit the application

Note: The "Open in Editor" feature uses your system's EDITOR environment variable. If it's not set, it defaults to nano.

🧠 Learning Resources

If you are new to C or need a refresher, here are some curated resources to help you out.

• 📖 Beej's Guide to C Programming: A fantastic, humorous, and deep guide to C. Highly recommended.
• 📖 The Book of C: A modern, concise summary of the C language.
• 🎥 Jacob Sorber: Excellent video explanations of C concepts and system programming.
• 🎥 Portfolio Courses: Clear, bite-sized video tutorials on specific C topics.
• 🔍 cppreference.com: The standard technical documentation for C.

Note: The progression of topics in these resources might differ slightly from the exercises here. For example, we introduce functions very early on!

📚 Syllabus

The exercises cover the following topics:

1. Intro: Basic C program structure, main function, and printf.
2. Variables: Integer types, float, char, and format specifiers.
3. Functions: Defining functions, arguments, return values, and prototypes.
4. If: Conditional logic (if, else if, else) and logical operators.
5. Loops: for loops, while loops, and nested loops.
6. Pointers: Address-of operator (&), dereferencing (*), and pass-by-reference.
7. Arrays: Declaring arrays, accessing elements, and iteration.
8. Strings: C-style strings (char arrays), string.h functions.
9. Structs: Defining structures, dot notation, and pointers to structs (->).
10. Memory: Dynamic memory allocation (malloc, free).
11. Bitwise: Bitwise operators (&, |, ^, ~, <<, >>) and bit masking.
12. Enums: Enumerated types (enum), typedef, and switch statements.
13. Command Line Arguments: argc, argv, string conversion (atoi), and parsing flags.
14. File I/O: Reading and writing text/binary files using fopen, fprintf, fscanf.
15. Storage Classes: static (local/global), global variables, and shadowing.
16. Testing: Assertions (assert), custom check functions, and floating point comparison.
17. Function Pointers: Declaring function pointers, callbacks, typedef for pointers, and arrays of functions.

🏗️ Projects

In addition to small exercises, there are larger "Capstone Projects" designed to test your understanding of multiple concepts at once.

• Classroom Manager (Topic 9): Build a complete Contact Management System using structs, arrays, and loops. You will implement features to add students, update grades, and calculate averages.
• Virtual CPU (Topic 12): Create a stack-based Virtual CPU that executes a custom bytecode. This project uses enums for opcodes, a stack for memory, and a fetch-decode-execute cycle.

⚖️ License

MIT