Practice & Mini-Projects

Knowing the syntax is 10% of programming. The other 90% is building things and debugging them. This topic exists to push you from "I read about C" to "I write C".

Daily Habit

Pick ONE small problem per day. 30 minutes is enough. Consistency beats marathons.

> The best C programmers got there by writing many small programs, not by reading one giant book.

How to Compile Like a Pro

# Strict warnings + address sanitizer + debug info
gcc -Wall -Wextra -Wpedantic -fsanitize=address -g main.c -o main

Fix every warning. Warnings are usually bugs in disguise.

Mini-Project Ideas (in order of difficulty)

Level 1 — A Few Hours Each

1. Number Guessing Game — pick a random number, prompt user, give "higher / lower" hints, count attempts. 2. Tip Calculator CLI — read bill amount and people, print per-person share with rounding. 3. Word Counter — read a file, count lines, words, characters (like Unix wc). 4. ROT13 / Caesar Cipher — encrypt/decrypt text with a shift key. 5. Temperature Converter — switch between Celsius / Fahrenheit / Kelvin.

Level 2 — A Day or Two

6. TODO List CLI — add / list / mark-done / delete tasks, persist to a text file. 7. Hangman — load random word from a file, manage guesses, draw the man. 8. Tic-Tac-Toe — 2-player on a 3×3 board, detect win/draw. 9. Phonebook — store contacts in a struct array, save/load to disk, search by name. 10. Linked List Library — implement push/pop/insert/remove/print + iterator.

Level 3 — A Week+

11. Dynamic Stack & Queue — generic, with malloc, free, grow/shrink. 12. Hash Table — with chaining; insert/get/delete in O(1) average. 13. Mini Shell — read a command line, fork/exec it, support pipes (Unix) or basic command parser (cross-platform). 14. JSON Parser — given a small JSON string, output a parsed structure. 15. Matrix Library — add/multiply/transpose/inverse; bonus: read from CSV.

Algorithm Practice Sets

Recommended Curated Sets

• HackerRank C track — hackerrank.com/domains/c — official C problems, easy to hard.
• HackerRank 30 Days of Code — daily mini-challenges, language-agnostic.
• CodeChef Beginner — codechef.com/practice/beginner — short, fast wins.
• GeeksforGeeks School — basics + small algorithm problems.
• LeetCode Easy → Medium — once you're comfortable, switch to LeetCode for interview-style problems.
• K&R Book Exercises — the original C exercises from "The C Programming Language" — still gold.

Debugging Toolkit

A Self-Test Checklist

If you can do all of these without looking, you've learned C properly:

• [ ] Read input from scanf and validate it
• [ ] Loop over an array and find max / min / average
• [ ] Reverse a string in place (no helper buffer)
• [ ] Implement strlen, strcpy, strcmp from scratch
• [ ] Allocate a dynamic array of n ints, fill it, free it correctly
• [ ] Implement a singly linked list with insert/delete/print
• [ ] Read a text file line by line and process each line
• [ ] Define a struct, pass it by pointer, modify it
• [ ] Write a recursive solution for factorial / Fibonacci / power
• [ ] Set, clear, toggle, and test a specific bit in a flag word

Where to Go From Here

C is the gateway to systems programming. After this you can pick:

Final Word

> "The only way to learn a new programming language is by writing programs in it." — Kernighan & Ritchie

You've finished the C track. Now go build something you find genuinely cool. The craft is in your hands. 🛠️