Problem with C code?

Question

linux

I read the book "UNIX Professional Programming" from the introduction, I do the first code example, a simple ls utility and an error appears (the code and the error are visible in the image). Who can explain how to fix it if possible in detail

Answer 1

Who can explain how to fix it if possible in detail

Answer 2

Compile the code. And see what errors the compiler throws. In my opinion, there will simply be no errors, the code is correct.
What you see is the glitches of the environment.
If there are errors, then publish the full code, as code, and not as a picture. Well, mistakes.
Now it’s impossible to understand what’s going on with you and reproduce it in principle because of the custom plug-in.