cli::interior_ptr<Type>' to 'cli::pin_ptr<Type>'

[jcvel]

Hello all:
I am new to C++/CLI,a nd I am trying to use a native dll.
I get the error "cannot convert from 'cli::interior_ptr<Type>' to 'cli::pin_ptr<Type>'"
DLL's declaration:

SI_STATUS WINAPI SI_GetNumDevices(
    LPDWORD lpdwNumDevices
    );
//I am pinning the pointer and call the dll with the error.
 
pin_ptr<long int> p = &dwNumDevices;
SI_STATUS status = SI_GetNumDevices(p);

What'swrong here ?
Thanks in advance !

[weaknessforcats]

You are passing a pin_ptr<long int> to a function expecting a LPDWORD.

However, a pin_ptr is a pointer - either const or volatile - and a long int does not qualify.

I expect you need :

pin_ptr<LPDWORD> p = &dwNumDevices;
SI_STATUS status = SI_GetNumDevices(p);
 

[jcvel]

TI found the problem:

pin_ptr<long int> p = &dwNumDevices;// This definition is ok. The thing is that DWORD is an unsigned long int, not a long int. Changing it to 'pin_ptr<unsigned long int> p = &dwNumDevices;' does the job.
I am not familiar with CLI that much.
Thanks anyways for your reply!

[weaknessforcats]

That would make sense since LPDWORD is the address of a DWORD and a DWORD is an unsigned int.

Considering you are in the Windows world, your pin_ptr should be a DWORD instead of an unsigned int. This may save problems should your code move to a place where a DWORD is not an unsigned int.

[jcvel]

You are very right on that !
I mixed the unsigned with the signed! I am an old C school yet !
Thanks