https://www.developer-tech.com/news/2018/jun/08/10-essential-resources-intermediate-c-programmers/

C is one of the most common languages taught at university, even though more modern languages like Java and Python are considered easier to learn. Why is that? Well, learning C is considered a good foundation for learning fancier languages later, as you get a better idea of what is going on behind the scenes by doing some things yourself. It's also widely used, forming the majority of code written to create Windows, Linux, Mac, databases, embedded systems and more.

In this article, we're going to share 10 essential resources for improving your C skills. Whether you're a new programmer who has mastered the basics of C, or you're moving into C from another language, we hope these tutorials, guides, references and projects are helpful.