So... Could someone show me how to code a monoalphabetic cipher? I have no clue where to even start.

OPTION STRICT It's always a good place to start from. :) 1st part of code in screenshot.

2nd part on code in screenshot.

This screenshot shows what it looks like when run twice. Only upper case A through Z are encoded / decoded. All other characters pass through unchanged. To decode, use the negative of the offset that was entered during encoding. e.g. if you encode with 7, use -7 to decode.

Thanks! I was lost, since I wanted to know how I can start off the coding for a vérenére cipher app, and I guess the screenshot shows that...