Does Win32 API use 64 bit length pointers on 64 bit system ?

Diakov Dmytro 1

Hi!
I have Win32 API (cloud filter api). On Windows 10 x64 it does not work when I create x64 app and pass IntPtr to it's function . (I have access violation memory exception).
But when I build x86 app and use IntPtr with 32 length it works.
So my question is: win32 api is 32 bitness API and can work only with pointers with 32 bits length, is it true ?

4 answers

David Lowndes 4,711 Reputation points

2020-12-21T12:22:41.527+00:00

On 64-bit Windows (with a 64-bit application), pointers are 64-bit.
You'll have to give some more details about what you're doing. Presumably there's something amiss somewhere.
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Diakov Dmytro 1 Reputation point

2020-12-21T12:29:22.693+00:00

I am using cloud filter api inside my .net application.
And when I call cfexecute function and passing there structure with a pointer inside it correctly works only when application platform is x86.
But when I am doing the same with x64 build platform it throws exception access violation memory.

David Lowndes 4,711 Reputation points

2020-12-21T12:46:01.04+00:00

As RLWA32 points out - ensure all aspects of your application are x64.

Diakov Dmytro 1 Reputation point

2020-12-21T13:02:50.51+00:00

When all aspects are using x64 or AnyCpu on x64 bit machine - it does not work.
When all aspects are using x86 on x64 bit machine - it works.

David Lowndes 4,711 Reputation points

2020-12-21T13:53:28.227+00:00

All I can say is that you're going to need to delve deeper to find the underlying source of the problem you have.

Diakov Dmytro 1 Reputation point

2020-12-21T13:58:13.827+00:00

So can you please tell, can Win32 API use pointers with 8 bytes size ?

David Lowndes 4,711 Reputation points

2020-12-21T14:05:02.957+00:00

Yes, although it's called "Win32", on a 64-bit Windows OS with a 64-bit application, pointers are 8 bytes.
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RLWA32 40,286 Reputation points

2020-12-21T12:36:30.74+00:00

Make sure that your managed code is actually running as 64-bit code. An IntPtr is 32-bits in 32-bit code and 64-bits in 64-bit code.

Check to make sure that you are not building managed code for AnyCpu with prefer 32-bits selected.
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Diakov Dmytro 1 Reputation point

2020-12-21T13:03:51.357+00:00

It works only when I am selecting building with prefer 32 bits.
Otherwise it will not work. Checked and sure about it.
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RLWA32 40,286 Reputation points

2020-12-21T13:22:35.213+00:00

An access violation can result for any number of reasons. Chances are that there is a problem in the code that is exposed when building for x64.
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Diakov Dmytro 1 Reputation point

2020-12-21T13:58:00.863+00:00

So can you please tell, can Win32 API use pointers with 8 bytes size ?

RLWA32 40,286 Reputation points

2020-12-21T14:04:05.59+00:00

As already stated, pointers in 64-bit code are 64-bits and pointers in 32-bit code are 32-bits.
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Rita Han - MSFT 2,161 Reputation points

2020-12-22T05:38:52.813+00:00

Hello @Diakov Dmytro ,

CfExecute API works well with 64 bit length pointers on 64 bit system in C++. You can test official sample: CloudMirror and get pointer size using sizeof(). The following snapshot shows an example and its result.

Thank you!

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Diakov Dmytro 1 Reputation point

2020-12-22T12:19:24.92+00:00

Hello @Rita Han - MSFT ,
thanks for your answer.

Yes, CfExecute works fine when passing pointer to single object.
But it fails when passing pointer to array.

RLWA32 40,286 Reputation points

2020-12-22T12:24:42.94+00:00

You really need to post the relevant snippets of code to provide the community with details.

Rita Han - MSFT 2,161 Reputation points

2020-12-23T02:21:12.367+00:00

As @RLWA32 pointed out, if you can share related code we can do a further investigation.
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