Advice needed : can an app developed in win7 64 bit run on 32 bit?

[reeve_netics]

hi
i want to develop an app in vb.net 2010 on win7 64bit environment.
will it be able to run in win7 32bit or win xp environments too.

tnx in adv.

[jmcilhinney]

Yes it will. If you set the target platform of the project to x86 then the app will run in 32-bit mode on both 32-bit and 64-bit Windows. If you set the target platform to Any CPU then the app will run in 32-bit mode on 32-bit Windows and 64-bit mode on 64-bit Windows. If you set the target platform to x64 then the app will only run on 64-bit Windows and it will run in 64-bit mode.

[reeve_netics]

tnx jmc.
which platform u would suggest.
1. x86,
2. any cpu,
3. x64.

i want the app should run in all environment (i.e. 64, 32 (win 7/ xp)
tnx

[jmcilhinney]

Well, you know the behaviour of the app for each option so what do you think it should be?

[Shaggy Hiker]

AnyCPU isn't always a good choice, though the places where it will fail are few. The one place I know it will fail is if you target an Access .mdb using the JET DB engine. There is no 64-bit JET DB engine, and if you target AnyCPU, the program will not drop back to using the 32-bit DB engine if it is running on a 64-bit system. That's the only drawback I know of, but the general pattern may hold true for other similar situations: If the program is running on a 64-bit system, it will look for 64-bit versions of resources, which may not exist (but probably do, and this particular issue only applies to using the JET DB engine against Access, which is kind of long in the tooth to begin with).

[reeve_netics]

thanks shaggy. we have face the same issue of access before. that's why i want to clear my doubts on that. bcoz our clients has different os (xp, win7 64bit). and we don't want to build projects on different machines (xp, win 7 64bit).

[jmcilhinney]

thanks shaggy. we have face the same issue of access before. that's why i want to clear my doubts on that. bcoz our clients has different os (xp, win7 64bit). and we don't want to build projects on different machines (xp, win 7 64bit).

I must have missed where you actually stated that earlier. We can't guess what's in your head. As I specifically stated in my first reply, x86 will force 32-bit mode on all systems so of you need 32-bit mode on all systems because you need to use a 32-bit library then obviously you should target the x86 platform. If you're not using 32-bit libraries then, while x86 won't hurt, you should select Any CPU.