Reading file in emacs

[Qiang Guo]

Hi,

I'm wondering if there is a way to read the content of files, say, to a
variable rather than a buffer ? Of course, one way to do
this is first read file into buffer and then edit the
buffer. Here comes my second question, how to process file
in a byte-by-byte fashion, for instance, instead of editing
a line of text, I'd like to edit directly their binary
representations ?

I know this is best done by C/C++, or some other
languages. However, I just wonder the possibility of doing
this in emacs, the greatest editor ever :-)

Thanks

Qiang