This repository accompanies Why Learn C by Paul J. Lucas (Apress, 2025).

Download the files using the green button, or clone the repository to your machine using Git.

Releases are numbered using a form of semantic versioning except instead of major.minor.patch, edition.errata.patch is used instead where:

• edition corresponds to the edition of the published book, e.g., 1 = first edition, etc.
• errata corresponds to a correction mentioned in the errata for the published book.
• patch corresponds to an update only to the “support” files in this respository, but not in the published book, e.g., makefiles, Autoconf macros, Gnulib source files, etc.

For example, release 1.0 corresponds to the initial code in the first edition without corrections; release 1.0.1 corresponds to updates to command-line options in makefiles and Autoconf macros, but no corrections to the published book; etc.

Many of the C examples are compiled and some are tested to ensure they're syntactically and semantically correct. A C compiler capable of compiling C23 via the -std=c23 option is required.

The git repository contains only the necessary source code. Things like configure are derived sources and should not be included in repositories. If you have autoconf, automake, and m4 installed, you can generate configure yourself by doing:

./bootstrap

or you can download a released version that contains configure.

After that:

./configure

If you need to use a compiler other than the first gcc found in the PATH environment variable, specify it via CC, e.g.:

./configure CC=clang

Finally, to build the source code for the larger examples:

make

If you get linker errors like "undefined reference to __atomic_load", add LDFLAGS=-latomic to your configure command.

Optionally, you can also run unit tests for the larger examples:

make check

See the file Contributing.md for more information on how you can contribute to this repository.

See the file Errata.md for errata to the published book.