Most of my recent programming has been on 32-bit Windows using C/C++/C#/VB6 . Lately, my customers are asking if my code will run on 64-bit Windows.
I'm wondering what legacy features I might be using that will break on 64-bit Windows? What are some real-world issues I need to think about and worry about?
Obviously, I will test my code on the 64-bit OS, but I'd like to know what common issues to look for. I more concerned with the existing binaries, but I am open to comments about what to worry about when recompiling (where possible).
EDIT: Here is a nice list of 64-bit porting bugs.
Viva64 tool - for check 64-bit programs: