Everything You Need to Learn C

A working repository for learning C from the ground up: the language itself, then memory, then the UNIX system call layer, then data structures, then real low-level projects.

It is organised as a curriculum rather than a scrapbook. The directory tree mirrors the six phases of ROADMAP.md, each phase is split into the topics it covers, and every phase carries a checklist of those topics, so the repository also serves as the progress tracker.

It currently holds 107 example programs, 97 of which are directly runnable.

Contents

• Repository layout
• Requirements
• Getting started
• Building and running
• Conventions
• Tracking progress
• Expected compiler warnings
• Reference material
• License

Repository layout

Path	Contents	Examples
phase-0-foundations/	Datatypes, storage classes, qualifiers, operators, control flow, functions, build basics	45
phase-1-language-core/	Compilation model, types and memory, pointers, arrays and strings, I/O, structs and unions and enums	42
phase-2-memory-mastery/	Memory layout, malloc/free/realloc, void pointers, dynamic structures	13
phase-3-system-level/	File descriptors, process control, signals, pipes and IPC, error handling, buffers, binary I/O, threads	6
phase-4-data-structures/	Stacks, queues, linked lists, hash tables, binary trees, recursion, searching, sorting	1
phase-5-projects/	End-of-roadmap projects: a shell, an allocator, an ELF parser, a text editor	0
docs/	Reference PDFs
vendor/libcs50/	The CS50 helper library, used by a handful of examples
tools/	Third-party installers, kept out of the working tree

The phases are numbered in the order they should be worked through, and so are the topic folders inside each one. Later phases are deliberately sparse: they are the work still ahead.

Requirements

Tool	Purpose
gcc or clang	Compiling the examples; the Makefile defaults to gcc
make	Driving every build in the repository
gdb	Required by the Phase 1 debugging exercises
valgrind	Required by the Phase 2 memory exercises

On Arch Linux:

sudo pacman -S base-devel gdb valgrind

On Debian or Ubuntu:

sudo apt install build-essential gdb valgrind

Getting started

git clone git@github.com:ExploitEngineer/EveryThing_youNeed_ToLearn_C_Language.git
cd EveryThing_youNeed_ToLearn_C_Language

# confirm the toolchain works: compiles all 107 examples
make check

# run the first one
make run FILE=phase-0-foundations/00-getting-started/hello-world.c

Then open phase-0-foundations/README.md and work down its checklist.

Building and running

Every example builds through the root Makefile at -std=c17 -Wall -Wextra -g. There is no per-directory build file to maintain.

Command	Effect
make run FILE=<path>	Compile one example and run it
make run FILE=<path> ARGS="..."	Same, passing arguments to the program
make build FILE=<path>	Compile only, leaving the binary in build/
make check	Compile everything, keep going on failure, print a summary
make all	Compile everything, stopping at the first failure
make list	List every example that defines a main()
make clean	Remove build/

make run FILE=phase-1-language-core/03-pointers/pointer-basics.c
make run FILE=phase-3-system-level/02-process-control/argv-greet.c ARGS="world"
make check

Three link-time details are handled automatically, so they never have to be passed by hand:

Detected in the source	Added to the command line
#include "foo.h" with a sibling foo.c	foo.c
#include <cs50.h>	-Ivendor/libcs50/src vendor/libcs50/src/cs50.c
#include <threads.h> or pthread	-pthread

For the rare case where a header name does not match its implementation file, pass the extra translation unit explicitly:

make run FILE=driver.c EXTRA="helper.c"

Compiled binaries are written to build/, which is ignored by git. To use a different compiler, override CC:

make check CC=clang

Conventions

File names describe what the example demonstrates, so both grep and shell completion are useful: pointer-arithmetic.c, stack-overflow-vla.c, realloc-grow-array.c.

Some examples are library translation units with no main(), paired with a header of the same name, such as swap-ints.c and swap-ints.h. These compile but do not link on their own. Writing the driver program for them is part of the exercise.

Tracking progress

Each phase README lists that phase's topics as checkboxes. A ticked box means a working example exists in the repository; an unticked box is a gap still to fill. This is the fastest way to see what is left:

grep -rn '^- \[ \]' phase-*/README.md

ROADMAP.md holds the full plan the structure is derived from, including the exercise lists and end-of-phase goals.

Expected compiler warnings

make check is expected to report zero failures. A small number of files still produce warnings deliberately, and should not be "fixed":

File	Warning	Reason
phase-0-foundations/01-datatypes/primitive-types.c	-Wunused-variable	A catalogue of type declarations; nothing is meant to be used
phase-0-foundations/01-datatypes/initialization-forms.c	-Wunused-variable	Same
phase-0-foundations/01-datatypes/typedef-basics.c	-Wunused-variable	Same
phase-0-foundations/03-operators/arithmetic-operators.c	-Wunused-variable	Operands left in place so the commented-out operators can be tried one at a time
phase-1-language-core/04-arrays-and-strings/array-basics.c	-Wunused-variable	Shows two array declaration forms, only one is iterated
phase-1-language-core/04-arrays-and-strings/string-literal.c	-Wunused-variable	A one-line declaration example
phase-1-language-core/03-pointers/uninitialized-pointer-segfault.c	-Wuninitialized	The undefined behaviour is the lesson
phase-1-language-core/03-pointers/uninitialized-memory.c	-Wmaybe-uninitialized	Same

Any warning outside this list is a real defect and worth fixing.

Reference material

• docs/c-cheatsheet.pdf for quick syntax lookup
• docs/c-complete-notes.pdf for longer explanations
• learn-c.org for interactive drills
• Modern C, 2nd edition as the reference text

vendor/libcs50/ is Harvard's CS50 helper library, vendored because several examples carried over from CS50 lectures depend on it. It is third-party code and is not part of the curriculum.

License

Released under the MIT License. See LICENSE for the full text.