how to define function pointer in C#

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ZhangZQ - 31 Oct 2003 03:38 GMT

if there is a function in a win32 dll, it is definition is

int add(int a, int b);

how to define that function pointer in C#?

thank you very much!

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Chris Taylor - 31 Oct 2003 04:03 GMT

Hi,

You would use a delegate.

delegate int AddCallback( int a, int b );

Hope this helps

Chris Taylor

> if there is a function in a win32 dll, it is definition is
>
[quoted text clipped - 3 lines]
>
> thank you very much!

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ZhangZQ - 31 Oct 2003 04:03 GMT

Thanks,

In C the GetProcAddress can get the function pointer, for example

typedef int (*MYADD)(int, int);
MYADD add = (MYADD) GetProcAddress(hMyLib, "add");

but how to pass the function pointer to that delegate?

Thank you very much again!

> Hi,
>
[quoted text clipped - 13 lines]
> >
> > thank you very much!

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Chris Taylor - 31 Oct 2003 04:33 GMT

Hi,

If you are going to bind statically to the function then you could use
interop aka P/Invoke from the System.Runtime.InteropServices name space.

[DllImport("dllname.dll")]
public int Add( int a, int b );

If you want to do this dynamically it is a little more work, I believe there
is a solution using the Relection Emit however I would rather want to test
this before commiting to it here :). But in principal, an I believe this
should answer your other post as well. You could use the Reflection classes
to create a temporary Assembly that can use interop to load the function and
use the Reflection Emit to create a .NET function which would perform the
actual invocation of the method. Being 5:31 in the morning I might just be
dreaming here but if I get a chance I will give it a try and post my
results.

The following is a more hardcoded approach to what I am suggesting, it might
get you going
http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=ueqNoUdtCHA.254
0%40TK2MSFTNGP10

Cheers

Chris Taylor

> Thanks,
>
[quoted text clipped - 24 lines]
> > >
> > > thank you very much!

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ZhangZQ - 31 Oct 2003 04:37 GMT

Wah!!! great, you are really an expert.

Thank you very much!

> Hi,
>
[quoted text clipped - 16 lines]
> The following is a more hardcoded approach to what I am suggesting, it might
> get you going

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=ueqNoUdtCHA.254
0%40TK2MSFTNGP10

> Cheers
>
[quoted text clipped - 28 lines]
> > > >
> > > > thank you very much!

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Fabian Schmied - 31 Oct 2003 21:43 GMT

> In C the GetProcAddress can get the function pointer, for example
>
> typedef int (*MYADD)(int, int);
> MYADD add = (MYADD) GetProcAddress(hMyLib, "add");
>
> but how to pass the function pointer to that delegate?

In addition to what Chris Taylor posted, I thought you might also be
interested in http://www.bearcanyon.com/dotnet/#getprocaddress, this sounds
pretty similar to what you want to achieve.

Fabian

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how to define function pointer in C#

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