how does i write a hex editor?

I want to writer an exe trainer for a game that hex edits another program (the game) to hack it/train it.

I know what addresses to edit and stuff, but I need to know what language would be best to write it in.

Any idea?

>>24
He wants to write a program that edits the code in memory of another program which is already running. On every modern OS except certain research OSes, this very much won't be allowed.