Nice simple, I hope, question

[Mad Axeman]

I'm pretty sure I know the answer but, if a program is created on a 64 bit PC will it run on a 32 bit PC or will it need to be recompiled on an older 32 bit PC?

[bplus]

My guess is it will have to be recompiled. I would bet real money! My argument, look at QB64pe you have a 64 bit version and a 32 bit version.

[SMcNeill]

It all depends on which compiler you use to compile with.

If you use the 32-bit version of QB64, the exe will run on both 32-bit and 64-bit machines.

If you use the 64-bit version of QB64, the exe will only run on 64-bit machines.

Note that 32-bit comes with various limitations that 64-bit doesn't, with the biggest being a difference in DECLARE LIBRARY packing/spacing and the limit of about 1.5GB of max memory usage for your program.  (32-bit has a true 2GB memory limit, but the system needs to reserve some space for itself, so anytime after about 1.5GB, you're pushing the limits and dancing on the edge of an "out o memory" error.)

[Mad Axeman]

I thought that may be the answer. Most of my programming is done on 64bit but I do have a Panasonic Toughbook CF-19 that's still running 32bit Win 7 and some of the software I use for work on it won't run under 64bit so looks like I'll need to compile two versions of everything. Not a problem luckily :-)

[SMcNeill]

You don't *have* to have two versions, as long as the 32-bit version is sufficient enough for your needs.

32-bit applications run on 64-bit machines.
64-bit applications *don't* run on 32-bit machines.

You determine which application you want when downloading from the github.  If you just grab the 32-bit version of QB64 and use it (with the differences I mentioned before in total application memory usable and packing and such with API calls), then any EXE you compile with it will be 32-bits and will be useable on both 32-bit and 64-bit systems.