C++: Decoding and Encoding from file?

[jE8qM4Gy]

I have to decode and encode data from a file
I just finished the decoding part. There is a file containing 5-6 digits integers that be separated by even or odd and then the even integers decoded to ascii char.

Now I have to do the opposite. I have a new file with ascii char that i need convert to 5-6 digits even and odd integers.

How do I begin ?I've already read in the char from the file.


Here's a link, this is the ascii char read from the file to the screen.
https://www.dropbox.com/s/sa7r70hpfnsttzg/C%2B%2B.jpg?m