how to define function pointer in C#

  • Thread starter Thread starter ZhangZQ
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ZhangZQ

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!
 
Hi,

You would use a delegate.

delegate int AddCallback( int a, int b );

Hope this helps

Chris Taylor
 
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,

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.2540@TK2MSFTNGP10

Cheers

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

Thank you very much!

Chris Taylor said:
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.2540@TK2MSFTNGP10

Cheers

Chris Taylor

ZhangZQ said:
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!
Click to expand...
Click to expand...
 
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?
Click to expand...

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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