c-koans/c_koans

C Koans

c_koans

A kōan 公案 (pinyin: gōng'àn) is a story, question, or statement, which is used in Zen practice to provoke the "great doubt" and test a student's progress in Zen practice.

Inspired by ruby koans you may learn the syntax and practices of C through a series of lessons in the form of Unit tests. These preprepared tests are all failing, by going through each one and repairing them to make them pass you will learn a small component of the C programming language.

The test are written in the Criterion unit testing library.

How to run

On Linux/OSX:

1. Install Criterion
2. run make clean all
3. run bin/c_koans
4. Start fixing!

On Windows:

1. Get a Linux command line (Cygwin, Windows Linux Subsystem, or whichever you prefer)
2. Follow the Linux/OSX instructions!

Sections

Inside src/ you will find a file for each of the following topics in C:

• Basics
• Pointers
• Functions
• Arrays
• Strings
• The Preprocessor
• Control Statements
• Structs
• Dataclasses
• I/O
• Malloc
• Linked List Project

The recommended order for fixing the tests is:

• about_basics.c
• about_control_statements.c
• about_functions.c
• about_pointers.c
• about_malloc.c
• about_arrays.c
• about_strings.c
• about_structs.c
• about_dataclasses.c
• about_printing.c
• about_io.c
• about_linked_lists.c
• about_preprocessor.c

c_koans's Issues

No actual reallocation and UB in about_arrays.c

In the file about_arrays.c on line 81 the array int is allocated with 5 elements (defined on line 80), then in line 96 this array is reallocated again with 5 elements (with the same size variable), and then access to the 6th (on index 5) element of the array (of 5 elements) is undefined behavior

bin/c_koans has no output

after running make clean all, ./bin/c_koans/ has no output.

Invalid assert in about_printing.c:27

There is a possible issue in the assert flag where it is expecting "A" from stdout, but a garbage result is actually returned from the stream.
Thanks for making this tho :)

Error in file about_io.c (error: cast to 'FILE *')

When compiling with :

gcc -v
Configured with: --prefix=/Library/Developer/CommandLineTools/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 9.1.0 (clang-902.0.39.2)
Target: x86_64-apple-darwin17.7.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

or

(brew --prefix llvm)/bin/clang --version                                                                                           ✓  10066  08:40:09
clang version 8.0.0 (https://llvm.org/git/clang.git 5e499dd14cc6493f0bd62bc6b95580837fb4303f) (https://llvm.org/git/llvm.git 740597761a32c90575ff6c2b2a6245fb2700f565)
Target: x86_64-apple-darwin17.7.0
Thread model: posix
InstalledDir: /usr/local/opt/llvm/bin

On MAC os X high sierra, I allways get executing make clean all:

rm -f -r build bin
/usr/local/opt/llvm/bin/clang -std=gnu11 -Wall -Werror -Wno-unused-function -I include src/about_io.c -c -o build/about_io.o
src/about_io.c:81:26: error: cast to 'FILE *' (aka 'struct __sFILE *') from smaller integer type 'int' [-Werror,-Wint-to-pointer-cast]
    fputs("Hello World", TODO_FP);
                         ^
include/c_koans.h:10:17: note: expanded from macro 'TODO_FP'
#define TODO_FP (FILE*)!NULL
                ^
src/about_io.c:82:26: error: cast to 'FILE *' (aka 'struct __sFILE *') from smaller integer type 'int' [-Werror,-Wint-to-pointer-cast]
    fputs("Hello World", TODO_FP);
                         ^
include/c_koans.h:10:17: note: expanded from macro 'TODO_FP'
#define TODO_FP (FILE*)!NULL
                ^
src/about_io.c:146:19: error: cast to 'FILE *' (aka 'struct __sFILE *') from smaller integer type 'int' [-Werror,-Wint-to-pointer-cast]
    fputs(TODO_S, TODO_FP);
                  ^
include/c_koans.h:10:17: note: expanded from macro 'TODO_FP'
#define TODO_FP (FILE*)!NULL
                ^
3 errors generated.
make: *** [build/about_io.o] Error 1