I/O with files, deleting.

I am making a small program that works on a file. I sometime need to delete a line of a peice of the file.

I checked many pages and tutorial, but it seems none had my problem before... :(

How can I, for example delete from the char 1000 to the char 1200 of a opened file?

Thanks in avance.

Edit: I'd prefere avoiding to load the whole file in RAM, modify it as array of char and rewrite it, since I may need to open big files.
I'll do only if there are no other ways...

By opening another file for writing, which you copy all the characters you want to keep.