Why should text files end with a newline?

Question

I assume everyone here is familiar with the adage that all text files should end with a newline. I\'ve known of this \"rule\" for years but I\'ve always wondered — why?

Answer 1

Basically there are many programs which will not process files correctly if they don't get the final EOL EOF.

GCC warns you about this because it's expected as part of the C standard. (section 5.1.1.2 apparently)

"No newline at end of file" compiler warning