Challenges

Foundations 1

Build your C basics: output, arguments, and the alphabet.

Strings & Bits

Strings, conversions, and bitwise operations in C.

Lists, Math & Bases

Strings, lists, math, and number bases in C.

Algorithms & Parsers

The deep end: interpreters, parsers, and harder algorithms. Twice as long, twice as deep.

Strings from Scratch

Reimplement C's string toolkit by hand: searching, concatenation, and the bounded strn-functions with their classic pitfalls.

Memory & Pointers

Work directly with raw bytes through void pointers: filling, copying, the overlap-safe move, and dynamic allocation.

Rebuild the C Standard Library

The capstone: reimplement the heart of libc by hand, from the ctype predicates all the way to a working printf.

Mastery

A timed C challenge covering text transforms and libc-style utilities

Algorithms & Parsing

A timed C challenge covering stream parsing, recursion, combinatorics, and search

Systems & Processes

A timed C challenge covering process pipelines, signals, and compact parsers

Network Systems

A single-task C challenge: build a non-blocking TCP server that relays messages between many simultaneous clients on the loopback interface, with zero memory or file-descriptor leaks

Grids & Simulation

A timed C challenge on parsing a 2D grid, dynamic programming over it, and running a cellular simulation

Pointers & Memory

A timed C challenge on reaching values through pointers, walking arrays inside their bounds, and owning every byte you allocate

C Language Core

A timed C challenge on integer types, conversions and overflow, then on modelling data with structs, unions and enums

Data Structures

A timed C challenge on walking and re-linking nodes, then on the stacks and trees that evaluators are built from

Sort & Search

A timed C challenge on the invariant a sort establishes, the bricks it is built from, what it costs, and sorting anything at all