I am writing a C++ .NET wrapper around some native C functions to provide a .NET interface for these functions for my C# application.
I want to link a static library and call some of its functions that use a pointer to a native char buffer.
I want my C++ .NET code to do this:
int nBytes = 100;
Byte[] byteArray = new Byte[nBytes];
external_Cfunction(byteArray, nBytes);
// Where external_CFunction is declared as:
void external_CFunction(char* charArray, int nbytes);
I don't have the source code for external_CFunction, just the .h include file and the static library.
How do I call the C function, which expects a pointer to a native C character array, with a parameter which is a reference to a .NET Byte[]
Thanks, David.
Linking static libraries in Visual C++ + passing Byte[] to native C functions?
Andranik Khachatryan
Thanks, this has been a great help.
David.
sgujjar
You have two options:
1) Allocate unmanaged memory block using Marshal::AllocHGlobal function, copy byteArray to it using Marshal.Copy function, and call C function with pointer returned by Marshal::AllocHGlobal.
2) Using GCHandle structure you can get unmanaged pointer to managed array. To do this, create GCHandle instance using GCHandle.Alloc(byteArray , GCHandleType::Pinned), and get unmanaged pointer using GCHandle.AddrOfPinnedObject method. Pass this pointer to C function.
In both cases you get IntPtr instance which can be converted void* using IntPtr.ToPointer method, and casted to char*.