头文件

public:
 STDMETHOD(GetEsamVersion)(BSTR* pVersion,int* nRet);

在项目.idl文件里添加

interface ITool : IDispatch
 {

  [id(9), helpstring("method GetEsamVersion")] HRESULT GetEsamVersion([in,out]BSTR* pVersion, [out,retval]int* nRet);
 };

cpp文件

STDMETHODIMP CTool::GetEsamVersion(BSTR* pVersion,int* nRet)
{

}