As soon as you realise that having more than one source file would be a good idea, most of the "prototype or not" arguments go away.
> Are there also other benefits to putting your non-main functions after main?
If you prefer a top-down view of the program, you get to see main() first just by scrolling through the code.
There are other oddities in your short example.
- using a while loop where a for loop would have made more sense.
- using parentheses on the
return statement.