一段VC调用IDispatch的原理性代码

给你一段VC调用IDispatch的原理性代码（摘自我的讲义，无版权）

IDispatch 调用 DispDll.Fun 组件中的Add加法函数

::CoInitialize(NULL);
HRESULT hr;
IDispatch *pDispatch=NULL;
try
{
    CLSID clsid;
    hr=::CLSIDFromProgID(L"DispDll.Fun",&clsid);
    if(FAILED(hr))    throw(0);

    hr=::CoCreateInstance(clsid,NULL,CLSCTX_SERVER,
        IID_IDispatch,(LPVOID *)&pDispatch);
    if(FAILED(hr))    throw(0);

    OLECHAR *arrFunName[]={L"Add"};
    DISPID dispID;
    hr=pDispatch->GetIDsOfNames(IID_NULL,arrFunName,1,LOCALE_SYSTEM_DEFAULT,&dispID);
    if(FAILED(hr))    throw(0);
    VARIANT v[2];
    v[0].vt=VT_I4;    v[0].lVal=3;    //加数（参数2）
    v[1].vt=VT_I4;    v[1].lVal=2;    //被加数（参数1）
    DISPPARAMS params={v,NULL,2,0};
/*    params.rgvarg=v;
    params.rgdispidNamedArgs=NULL;
    params.cArgs=2;
    params.cNamedArgs=0;
*/
    VARIANT vResult;
    hr=pDispatch->Invoke(dispID,IID_NULL,LOCALE_SYSTEM_DEFAULT,DISPATCH_METHOD,
            ¶ms,&vResult,NULL,NULL);
    if(FAILED(hr))    throw(0);
    CString s;    s.Format("%d",vResult.lVal);
    AfxMessageBox(s);
    pDispatch->Release();
}
catch(...)
{
    if(pDispatch)    pDispatch->Release();
}
::CoUninitialize();