As a programmer, what do I need to worry about when switching to 64-bit windows?


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.


20 issues of porting C++ code on the 64-bit platform

The forgotten problems of 64-bit programs development

64 bits, Wp64, Visual Studio 2008, Viva64 and all the rest...

Traps detection during migration of C and C++ code to 64-bit Windows

AMD64 (EM64T) architecture


Viva64 tool - for check 64-bit programs:

Viva64: what is it and for whom is it meant?