How to call a c++ function from c# program

Question

Hi Can anyone of you tell me how to call c++ functions from c# program? I have a C++ dll in which i have some functions now i want to call them from my c# code. Please tell me how can i do this. If possible provide me sample code n all. Thank you in advance Bye sree

Alan · Answer

It depends on what sort of a C++ dll it is and what kind of a function you want to call. If it's a 'pure' managed C++ dll (written in either managed extensions or C++/CLI) then you can add simply add a reference to the dll to your C# project instantiate its managed classes and call their functions as if they'd been written in C#. If it's an unmanaged C++ dll which exports a number of static functions (i.e. functions which not are members of a class) then you can call these using a procedure called Platform Invoke which uses the DllImport attribute. If it's an ATL dll (i.e COM) you should be able to access it from C# using COM interop. It it's an MFC dll or you are otherwise wanting to access member functions of an unmanaged C++ class then the only practical ways of doing this from C# are: 1. To recompile as a COM dll so that you can use COM interop. 2. To build an unmanaged C++ wrapper dll which wraps the member functions you want to call as static functions so that they can be called using Platform Invoke. 3. To build a 'mixed mode' managed C++ wrapper dll which wraps the unmanaged classes as managed classes so they can be used directly from C#. If the situation you have requires Platform Invoke then I'd read these two articles and MSDN tutorial to get a grasp of what this involves: http://msdn2.microsoft.com/en-gb/magazine/cc164123.aspx http://msdn2.microsoft.com/en-gb/magazine/cc163910.aspx http://msdn2.microsoft.com/en-us/library/aa288468(VS.71).aspx If it requires COM interop then I'd read this MSDN tutorial: http://msdn2.microsoft.com/en-us/library/aa645736(VS.71).aspx Otherwise if you can let me know what situation you have and which version of VS you're using I'll try and find some sample code.