How the labs work
C Labs are hands-on coding challenges that take you from the basics to complete projects, one small step at a time.
Every lab runs C right in your browser, so there is nothing to install. For each lab:
- Read the task, the input and output rules, and the example.
- Write your code in the editor and press Run to try it.
- Press Check to test it against hidden test cases. Your output must match exactly.
- Stuck? Read the hints, then open Show solution for a full explanation.
Start with the first lab: Hello, World! →
Chapters
- 01 · Output with printf (8 labs)
- 02 · Variables & Types (8 labs)
- 03 · Input & Arithmetic (8 labs)
- 04 · Conditions (8 labs)
- 05 · Loops (8 labs)
- 06 · Loop Control & Patterns (8 labs)
- 07 · Functions (8 labs)
- 08 · Recursion (7 labs)
- 09 · Arrays (8 labs)
- 10 · 2D Arrays (6 labs)
- 11 · Strings (8 labs)
- 12 · String Algorithms (8 labs)
- 13 · Pointers (7 labs)
- 14 · Pointers, Arrays & Strings (6 labs)
- 15 · Dynamic Memory (5 labs)
- 16 · Structs (6 labs)
- 17 · Enums, Unions & Bits (6 labs)
- 18 · Preprocessor & Macros (5 labs)
- 19 · Linked Lists (6 labs)
- 20 · Stacks & Queues (5 labs)
- 21 · Sorting & Searching (6 labs)
- 22 · Number Algorithms (6 labs)
- 23 · Text Processing (5 labs)
- 24 · Projects (6 labs)