The C Programming Language (K&R)

Solutions for every exercise from "The C Programming Language" by Kernighan / Ritchie.

Goals

This was the first "classic CS book" that I read; in addition to learning C, I also learned how to write code productively and how to read a CS textbook. As such, my goals for this textbook changed as I read it (especially given that I jumped around a good bit). I settled on the following definition for "complete":

• All pages read, including the appendices
• All exercises solved, with maximum const correctness
• All solutions compile against C11 with -Werror -Wall
• All solutions report no issues from Clang's static analyzer (scan-build), excluding false positives
• All solutions report no memory leaks in valgrind when run with --leak-check=full --show-leak-kinds=all

I have not tried to hold to the text as closely as possible at the cost of writing straightforward code; e.g. I may use structs in my solutions in chapter 5 despite them not being introduced til chapter 6.

Running via Makefile

All exercises are built via Makefile and should be executed from the top-level of the repo, inside the Dockerized workspace (see makefiles/docker.mk for targets to create this workspace).

Every exercise either has its own target (e.g. make 5.4 will make exercise 4 in chapter 5) or is grouped into a subproject with its own target (e.g. 5.14 - 5.17 are all about the sort program, so they exist in ch-5/sort/ and are built with make sort). Chapters also have their own targets (e.g. all exercises from chapter 6 are buildable with make ch-6), and make all builds everything. All buildable targets are listed in the top-level Makefile, at the botom.

The Makefile system is divided into four parts:

• Chapter-specific Makefiles containing specific patterns for building and testing individual exercises.
• A docker.mk for managing the Dockerized workspace.
• A buikding.mk containing build settings; you can find targets for producing binaries and toggle valgrind, static analysis, and tests from this file.
• A top level Makefile tying everything together; all exercises should be built in the top-level directory of the repo.

Top Highlights

• ch-8/malloc_j/ - a storage allocator / the final boss of K&R
• common/trees/ - a generic binary search tree library I wrote to handle exercises in Chapter 6
• ch-8/fopen_j/ - buffered FILE I/O
• common/tests/ - a simple unit testing library that wraps around the assert(3) macro; I wound up not using this too much beyond ch-1 as my testing stategy evolved.
• faq/ - Experiments / questions I had to test my understanding of C as I read K&R.

Conventions

I have my editor set up to run clang-format -i --style=Google on save.

Notes about the exercises

• Each chapter / subproject has its own README.md; see these for specific notes.
• For programs reading from stdin, it is expected behavior that you will need to hit CTRL-D twice to exit if the last character entered was not a newline - this behavior is defined by the POSIX standard (see this Stack Overflow question).

Source text

You can find the full 2nd edition text with examples here. You can find problem statements and solutions here.

Special thanks

• Elliott Jin for the many hours of help with debugging and review.
• Steven Harris for feedback on the RPN calculator.
• Michael McLoughlin for help on buffered FILE I/O.
• Bartosz Wróblewski for feedback on the memory allocator.