Wrap c++ function that needs function pointer

Question

i have an external dll (with C++ documentation on how to use it) and i need to use some functions inside of it from my C# program.

I wrote a little wrapper for some functions and they works well, but i don't know how to wrap functions that needs function pointer as parameter.

C++ documentations says:

uint NativeFunction(uint32 parameter, GenericFunction *func)

Since GenericFunction should get 2 *char as parameters i wrote this in C#:

public struct GenericFunction 
{
    public string param1;
    public string param2;
}

[DllImport("externalLib.dll", SetLastError = true)]
public static extern uint NativeFunction(uint parameter, GenericFunction func);

And when i need to call it i use

GenericFunction test = new GenericFunction();
uint result = NativeFunction(0u, test);

with this i have this ugly error:

Attempted to read or write protected memory. This is often an indication that other memory is corrupt.

I'm pretty sure i'm calling the function in a wrong way since i still have to define what GenericFunction do, but i have no idea how to do it and google is not helping me this time!

possible duplicate of PInvoke C#: Function takes pointer to function as argument — clcto
– clcto, Commented Sep 30, 2014 at 15:34
Because i didn't know how to pass a function pointer as a parameter, so a struct "looked" fine! I think the question marked as duplicate can really solve my problem, i'm doing some test — HypeZ
– HypeZ, Commented Sep 30, 2014 at 15:42

jbriggs · Accepted Answer · 2014-09-30 15:41:20Z

3

You can use delegates in place of a function pointer.

public delegate void GenericFunction(string param1, string param2);

[DllImport("externalLib.dll", SetLastError = true)]
public static extern uint NativeFunction(uint parameter, [MarshalAs(UnmanagedType.FunctionPtr)]GenericFunction func);

answered Sep 30, 2014 at 15:41

jbriggs

3532 silver badges10 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

HypeZ Over a year ago

this looks good, but how can i define what "GenericFunction" does? I need to declare with a sort of delegate?

clcto Over a year ago

@HypeZ Just as you would use other delegates. Create a function with the same signature and pass the name of that function to the NativeFunction

Collectives™ on Stack Overflow

Wrap c++ function that needs function pointer

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related