What is the ASCII value of eof?

Answer 1

This is lost knowledge territory, in the sense that the references I was reading seem to be confusing the ASCII character and the EOF constant / status flag.

The EOF constant is a flag that indicates you can not read any more.
There is no point in reading after the flag is sent.

The ASCII character code for "eof" is 26 (Ctrl-Z). It has special text file meaning.
While not a hard limit (and you can still read) text modes will truncate at that character.

This code demonstrates ASCII 26 truncating a text-mode read:
https://code.sololearn.com/cyt3z1m2z69Q/?ref=app

It's not just buffered reads; some codes using readln will also inexplicably stop short if someone gets ASCII 26 in a text-mode file.

Answer 2

Thank you.

Answer 3

depends on the compiler, generally it's -1