1.  If errno contains a nonzero number, is there an error?

2.  What is a stream?

3.  How do you redirect a standard stream?

4.  How can you restore a redirected standard stream?

5.  Can stdout be forced to print somewhere other than the screen?

6.  What is the difference between text and binary modes?

7.  How do you determine whether to use a stream function or a low-level function?

8.  How do you list files in a directory?

9.  How do you sort filenames in a directory?

10.  How do you determine a file's attributes?