C is an old language lacking many, many, many modern features. One of the features it does not lack is encapsulation and isolation.

I have a love hate relationship with C. I love the simplicity of the language. Although it is simpler, it is certainly possible to emulate many features found in other languages like the encapsulation, though rarely perfectly, and not every feature.

I also like C because I am dealing with code at a lower level leads me to having a much better understanding of what is happening under the hood. However, this lower level access allows you to accidentally write bad code that could introduce a vulnerability

I'm surprised to hear that anyone would complain about this with C. Even the Wikipedia page about encapsulation cites C as a non-OOP language example.

Thank you for the article. Opaque struct is an interesting subject for people who want to go deeper into their understanding of C.

If I could add/emphasis two points to the article:

• FILE is a famous example of struct using this trick. So, even if yon don't often need to develop an opaque struct in C, you certainly use such struct daily without knowing.

• you can't declare a variable with an opaque type (because the compiler would need to know its size). Everything must be handled through pointers, and the library has to provide functions to allocate/destroy the struct, like fopen() and fclose() for FILE.