It uses the gcc compiler so C, or C++ can be applicable.
That being said, this book teaches network programming from the ground up so I would recommend understanding how to compile and output C code, then go through the book.
If you run into keywords, or syntax that you are not familiar with, just google it, and then keep working through the examples.
Mind you, the key takeaways from this book are not how to network practice IN C, but general practices. This knowledge can be applied to plenty of other languages such as Rust.
That being said, this book teaches network programming from the ground up so I would recommend understanding how to compile and output C code, then go through the book.
If you run into keywords, or syntax that you are not familiar with, just google it, and then keep working through the examples.
Mind you, the key takeaways from this book are not how to network practice IN C, but general practices. This knowledge can be applied to plenty of other languages such as Rust.