Thread: Which functions set status indicators?

Originally Posted by The C Programming Language, 2e

Many of the functions in the library set status indicators when error or end of file occur. These indicators may be set and tested explicitly. In addition, the integer expression errno (declared in <errno.h>) may contain an error number that gives further information about the most recent error.

I wonder which functions set status indicators. Could you please give me a list of those functions? Thanks.