Use of COM smart pointers

Speak with code

ComTest implements two interfaces: ICmd, IStr, and ICmd. There is a function -- Add, and IStr has a function -- Cat, which is used to describe the usage of smart pointers, so it is not listed, the attachment contains the project code. The COM component does not provide the source code.

 
 

  
  
# Include <atlbase. h>
  
  
# Include <atlcom. h>
  
  
 
  
  
# If 0
  
  
# Import "ComTest. tlb" no_namespace // The third method uses this line to import the tlb Type Library without namespaces
  
  
# Endif
  
  
 
  
  
// Use either of the following two methods:
  
  
# Include "ComTest_ I .c"
  
  
# Include "ComTest. h"
  
  
 
  
  
# Include <stdio. h>
  
  
# Include <stdlib. h>
  
  
 
  
  
Using namespace ATL;
  
  
 
  
  
Int main ()
  
  
{
  
  
CoInitialize (NULL );
  
  
# If 0
  
  
// Method 3
  
  
ICmdPtr cmd = NULL; // declare an ICmdPtr smart pointer and create an instance that is similar to the one used by ADO.
  
  
Cmd. CreateInstance (_ uuidof (Cmd ));
  
  
Int sum;
  
  
Cmd-> Add (1, 2, & sum );
  
  
Printf ("% d \ n", sum );
  
  
Cmd. Release (); // fo Yue: Indispensable
  
  
 
  
  
// Method 1
  
  
CComPtr <IUnknown> pUnk; // defines a smart pointer
  
  
CComQIPtr <ICmd> pCmd;
  
  
HRESULT hr;
  
  
 
  
  
Hr = pUnk. CoCreateInstance (CLSID_Cmd, NULL, CLSCTX_INPROC); // create an IUnknown instance on the pointer's COM. It's just a bit difficult to understand.
  
  
Hr = pUnk. QueryInterface (& pCmd); // equivalent to the object for creating ICmd
  
  
Int sum;
  
  
Hr = pCmd-> Add (1, 2, & sum );
  
  
Printf ("% d \ n", sum );
  
  
// Remember to Release
  
  
PUnk. Release ();
  
  
PCmd. Release ();
  
  
# Endif
  
  
// Method 2
  
  
CComPtr <IUnknown> pUnk;
  
  
PUnk. CoCreateInstance (CLSID_Cmd, NULL, CLSCTX_INPROC); // same as the first method
  
  
CComQIPtr <ICmd> pCmd = pUnk; // create an ICmd object
  
  
CComQIPtr <IStr> pStr = pUnk; // create an IStr object
  
  
Int sum;
  
  
 
  
  
PCmd-> Add (1, 2, & sum );
  
  
Printf ("% d \ n", sum );
  
  
CComBSTR bstr;
  
  
PStr-> Cat (BSTR) "d", (BSTR) "e", & bstr );
  
  
Printf ("% S \ n", bstr );
  
  
// Release is indispensable.
  
  
PStr. Release ();
  
  
PCmd. Release ();
  
  
PUnk. Release ();
  
  
 
  
  
CoUninitialize ();
  
  
System ("pause ");
  
  
Return EXIT_SUCCESS;
  
  
}
 
 

 

This article is from the "Studoc" blog, please be sure to keep this source http://studoc.blog.51cto.com/1284909/282721