<unknwn.h>STDMETHODIMP_(ULONG) STDMETHOD_(ULONG, AddRef)() PURE;

#include <unknwn.h>//*struct ISimpleMsgBox : public IUnknown{// IUnknown 方法    STDMETHOD_(ULONG, AddRef)() PURE;STDMETHOD_(ULONG, Release)() PURE;STDMETHOD(QueryInterface)(REFIID riid, void** ppv) PURE;  // ISimpleMsgBox 方法    STDMETHOD(DoSimpleMsgBox)(HWND hwndParent, BSTR bsMessageText) PURE;};//*///STDMETHOD()包含virtual关键字，返回类型和调用规范。//STDMETHOD_()也一样，除非你指定不同的返回类型。//PURE扩展了C++的“=0”，使此函数成为一个纯虚拟函数。STDMETHOD()和STDMETHOD_()有对应的宏用于方法实现——STDMETHODIMP和STDMETHODIMP_()。例如DoSimpleMsgBox()的实现：STDMETHODIMP CSimpleMsgBoxImpl::DoSimpleMsgBox ( HWND hwndParent, BSTR bsMessageText ){  ...}STDMETHODIMP_(ULONG)