Yes you can. You have to use Platform Invoke, pinvoke for short. Basically, you write a C# function declaration with a signature that's compatible with a C++ function in the DLL and then you apply the DllImport attribute to the function to map it to the appropriate function in the appropriate DLL. It's exactly the same way that .NET applications invoke the Windows API, e.g. calling FindWindow, FindWindowEx and SendMessage to set text in a text box or click a button in an external application.it's c++ api can I used that for c#?