Challenge 2: Compiling Without -o — Possible Solution
====================================================================

Given the same hello.c from the chapter:

    $ gcc hello.c
    $ ls
    hello.c   a.out

Omitting -o leaves gcc to fall back to its default output name,
a.out. Running it directly by that name:

    $ ./a.out
    Hello, C!

WHY THIS WORKS AS AN ANSWER
------------------------------
This confirms the exact behavior the chapter's warn-box names: no -o
flag means the executable is silently named a.out, not something
derived from the source filename (hello.c does NOT produce hello by
default) -- and it's run the same way as any other compiled
executable, with ./ in front of the name.