Convert VarPtr code in c# to c

Javier Flores

Hello!
can anybody helpme to resolve this, i tried to parse this c# code to c, but i failed.

public static int VarPtr(object e)
        {
            GCHandle GC = GCHandle.Alloc(e, GCHandleType.Pinned);
            int gc = GC.AddrOfPinnedObject().ToInt32();
            GC.Free();
            return gc;
        }

what exactly do these,and how i can write in c.

sorry, my english is bad.

4 Replies

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Sam Hobbs16y ago
Yes, that should work. If it were me I would use:
LPARAM valor=(LPARAM) (LPVOID) &data;
Both ways will compile the same but it is a good practice to use the designated type whenever possible.
Javier Flores16y ago
Ok i understood but this is the problem, for example, i use the VarPtr function and i convert the address to int32 and i if i have:

COPYDATASTRUCT data;
LONG_PTR valor=(LPARAM) (LPVOID) &data;

"valor" may content the equivalent ?

thanks.
Sam Hobbs16y ago
I am not familiar with GCHandle.AddrOfPinnedObject but as best as I understand what it does, it does two things. It first "pins" an object in memory so it is not moved, then it returns a pointer to that location. If you are converting code to all C code, no garbage collection, then there is no need to pin an object to memory; there is nothing that will cause the object to move around. So probably you just need to get the address of the object; so inothjer words, instead of VarPtr(object) you probably just need &object. Note however that COM uses smart pointers, or at least the C equivalent, so the object is probably already a ponter.
Are you totally sure you must convert to C? If it is possible to use C++, then that will be easier. Objects are by definition classes and C does not have classes but you can use COM objects in C but it requires more typing and such. I am not sure, but I assume you cannot use .Net in C.
theLizard16y ago
GCHandle is .NET which can be used with VB, C# and C++ but NOT C

You cannot convert this code to C.