[NaS]

Last line first, or completely reversed?

Imagine this is the content of your file:

Код:

hello
test

Should it become:

Код:

tset
olleh

or:

Код:

test
hello

It's also important to know how long the file is. If it's not too big it's easy to use a buffer and then go through that in reverse (either line by line or character by character). Otherwise you must use fseek and fgetchar. fseek has different modes you can take advantage of.