ArcGIS Engine Developer Guide

C++ APPLICATION PROGRAMMING INTERFACE
The following example illustrates how the three functions discussed above should
be used within an application.
In this code, both AoInitialize and IAoInitialize
are used. These are not the same thing:
AoInitialize is the API call discussed above, while
IAoInitialize is an ArcObjects interface used in
licensing.
Note that IAoInitialize must be scoped so that
it will be out of scope before AoUninitialize is
called.
int main (int argc, char* argv[])
{
// Initialize ArcGIS Engine and COM.
::AoInitialize(NULL);
// ArcGIS Engine licensing
{
IAoInitialize ipInit(CLSID_AoInitialize);
esriLicenseStatus status;
ipInit->Initialize(esriLicenseProductCodeEngine, &status);
// ArcObjects code here
}
ipInit->Shutdown();
// Uninitialize ArcGIS Engine and COM.
::AoUninitialize();
}
// Exit the application.
AoExit(0);
AoCreateObject
• AoCreateObject—used where CoCreateInstance would be used in COM programming.
extern "C" HRESULT AoCreateObject(REFCLSID rclsid,
LPUNKNOWN pUnkOuter,
DWORD dwClsContext,
REFIID riid,
LPVOID *ppv);
When using smart pointers, this function will not be needed. However, you
can create an instance of an object without smart pointers by using this function,
as shown in the following code:
// Create a Workspace Factory without using smart pointers.
IWorkspaceFactory *pWorkspaceFactory;
hr = ::AoCreateInstance(CLSID_ShapefileWorkspaceFactory, 0,
CLSCTX_INPROC_SERVER,
IID_IWorkspaceFactory,
(void **)&pWorkspaceFactory);
AoAllocBSTR and AoFreeBSTR
• AoAllocBSTR replaces SysAllocString.
extern "C" BSTR AoAllocBSTR(const OLECHAR *sz);
• AoFreeBSTR replaces SysFreeString.
extern "C" void AoFreeBSTR(BSTR bstr);
Chapter 4 • Developer environments • 225