The thing about C is that its library call API is generally how different languages interoperate: If you write a library in [insert language here] and you want

The thing about C is that its library call API is generally how different languages interoperate: If you write a library in [insert language here] and you want it to be callable in any other language, you need to make bindings for C. Likewise, if you're using any other language and you want to use a general library, you'll need to know enough C so that you can successfully encapsulate concepts like pointers; and copy your program's data into data structures that C can consume. It's all much, much easier if you have some C experience. In my case, I haven't done much C in 20 years. What really helped me "keep up" was occasionally doing Mac programming in Objective C. Because it's really easy to drop into C, it helped refresh me on a lot of the concepts. Even if you're doing Swift, you can mix in an class written in Objective C that's mostly straight C in the methods.