ArcGIS Engine Developer Guide

C++ APPLICATION PROGRAMMING INTERFACE
Notice the call to AddRef. This is required to
ensure that resources are managed properly.
}
IWorkspacePtr ipWork;
hr = ipWorkspaceFactory->OpenFromFile(CComBSTR(path), 0, &ipWork);
if (FAILED(hr) || ipWork == 0)
return E_FAIL;
// Initialize ipTinWorkspace with ipWork.
ITinWorkspacePtr ipTinWorkspace(ipWork);
*ppTinWorkspace = ipTinWorkspace;
// AddRef() if the assignment worked.
if (*ppTinWorkspace)
(*ppTinWorkspace)->AddRef();
return hr;
ESRI System interfaces
The System library within ArcGIS Engine, which is included with ArcSDK.h,
contains a number of interfaces that simplify programming. It contains components
that expose services used by the other ArcGIS libraries.
Groups of objects in interfaces without STL
ArcObjects contains several interfaces for managing groups of objects. Although
they are not all discussed here, the examples given illustrate some that can greatly
simplify your work with COM objects in C++. Standard Template Library types
similar to some of these exist; however, these interfaces are often simpler than
their STL counterparts and are already set up to be used with COM objects. For
additional details on any of the interfaces below, see ArcGIS Developer Help for
C++.
• IArray—provides access to members that control a simple array of objects.
There are multiple related interfaces, such as IDoubleArray and IVariantArray.
The following code snippet shows how to add the geometries of the features
in a FeatureCursor to an array.
// ipFeatureLayer is of type IFeatureLayerPtr and ipQueryFilter is of
// type IQueryFilterPtr. Both have already been declared and
// instantiated.
IArrayPtr ipCacheArray (CLSID_Array);
IFeatureCursorPtr ipFeatureCursor;
ipFeatureLayer->Search(ipQueryFilter, VARIANT_FALSE, &ipFeatureCursor);
IFeaturePtr ipFeature;
while (ipFeatureCursor->NextFeature(&ipFeature) == S_OK)
{
IGeometryPtr ipGeom;
ipFeature->get_ShapeCopy(&ipGeom);
ipCacheArray->Add((IUnknownPtr) ipGeom);
}
Chapter 4 • Developer environments • 229