C Demo Examples

Practice programs, one file each. Every demo is self-contained, commented, and free of unsafe legacy functions. Compile any of them with the safe recipe: gcc -std=c11 -Wall -Wextra -Werror file.c -o app, then run ./app (Windows: ./app.exe).

How to use: click View to open a file in the code viewer, read its comments, download it, compile it with the flags above, then modify it on purpose. The demos are ordered by lesson — start at 01 and work up.

Foundations

Syntax, variables, operators, control flow, loops, and functions from PHASE 1 and 2.

#	Description	Link
1	Hello, World	View
2	Variables & Types	View
3	Operators & Expressions	View
4	Control Flow	View
5	Loops	View
6	Functions & Recursion	View

Memory & Pointers

Pointers, strings, and heap management from PHASE 3.

#	Description	Link
7	Pointers & Dereferencing	View
8	Strings & the NUL Terminator	View
9	Dynamic Memory	View
10	Structs & Unions	View

Data Structures & Algorithms

Collections and the classic algorithms from PHASE 4.

#	Description	Link
11	Linked List	View
12	Dynamic Array (Vector)	View
13	Hash Table	View
14	Binary Search	View
15	Sorting: qsort & Quicksort	View
16	Recursion & Memoization	View
17	Sieve of Eratosthenes	View

Advanced & Systems

Callbacks, bit manipulation, and files from PHASE 5.

#	Description	Link
18	Function Pointers & Callbacks	View
19	Bit Flags & Masks	View
20	File I/O & errno	View

Practice move: after running each demo, break it: change a %d to %s, drop a free, or index past the end — then recompile with -fsanitize=address,undefined and watch the sanitizer name the exact bug.