Well C was my second language. I learned it on an amiga 500. But I quickly transitioned to a 386 (yes i know, a downgrade) but my dad put turbo c++ on it and I never wrote much ansi c after that. A bit for odd embedded targets, but mostly c++ my whole career. So I can write old fashioned c, and I don't start new projects in c, but writing c abi shims for c++ libraries or reading modern c is something I do with some frequency. Learning it would be fun maybe as I've never really used c99 or newer for anything.