Overview

After having been intrigued by Crystal's C interop facilities while reading through the docs, I decided to write a C library (my first!) and try linking it into a program. The library provides one function (hello), which accepts one parameter and uses it to print a heartfelt message (e.g. Hello, world!).

I ran into one issue along the way, but I believe that was a result of my ignorance about the C library ecosystem. I also went off the rails a bit because I was using a static library and not something available via pkg-config. Either way, once I figured out how to supply the path to my static library to @[Link], everything Just Worked.

Build

• pushd ./src/c && make && popd
• crystal build src/c-interop.cr

Run

./c-interop # => Hello, world!

Interesting bits

• ./src/c/lib/hello.c
• ./src/c-interop.cr

Resources

• http://www.cs.dartmouth.edu/~campbell/cs50/buildlib.html
• https://randu.org/tutorials/c/libraries.php