Linking and communication to AutoCAD in C++ - c++

Question

How can i open the AutoCAD application and send commands to that in C++?
In the VB it's possible by CreateObject and GetObject functions.

Answer 1

In C++, you need to use CoCreateInstance instead of CreateObject and CoGetObject instead of GetObject.
Here is some sample code, adapted from this sample of Microsoft:
// Initialize COM for this thread...
CoInitialize(NULL);
// Get CLSID for our server...
CLSID clsid;
HRESULT hr = CLSIDFromProgID(L"AutoCAD.Application", &clsid);
if(FAILED(hr)) {
return -1;
}
// Start server and get IDispatch...
IDispatch *pAcadApp;
hr = CoCreateInstance(clsid, NULL, CLSCTX_LOCAL_SERVER, IID_IDispatch, (void **)&pAcadApp);
if(FAILED(hr)) {
return -2;
}

Answer 2

You may want to use C# instead of C++, the .Net syntax is much more friendly than the C++ if you start to deal with COM pointers.
Here is an example. You can always create a .Net CLI library and wrap your C++ code so you can use it from .Net.
void LaunchACAD()
{
try
{
//Connect to a running instance
AcadApp = (AcadApplication)System.Runtime.InteropServices.Marshal.GetActiveObject(
"AutoCAD.Application");
}
catch(Exception ex)
{
// starts last run acad version
System.Type acType = System.Type.GetTypeFromProgID("AutoCAD.Application", true);
// ("AutoCAD.Application.17.1"); // starts 2008
// ("AutoCAD.Application.17.2"); // starts 2009
AcadApp = (AcadApplication)System.Activator.CreateInstance(acType);
}
AcadApp.Visible = true; // by the time this is reached AutoCAD is fully functional
}