如何避免OPC記憶體泄露

用OPC Client開發時，需要從如下幾個地方注意記憶體泄露：

（1）所有返回的指標，都要用CoTaskMemFree釋放，如：

function Group_TryAddItems(AGroupIntf:IOPCItemMgt;AItemCount:integer;AItems:POPCITEMDEFARRAY):POPCITEMRESULTARRAY;var  vErrors: PResultList;begin  Result:=nil;  vErrors:=nil;  if AGroupIntf.AddItems(AItemCount,PSafeArray(AItems),Result,vErrors)<>S_OK then  begin    CoTaskMemFree(Result);    Result:=nil;  end;  CoTaskMemFree(vErrors);end;

 

（2）用ISyncRead介面讀取資料後，要用VariantClear釋放，如：

function  Group_ReadItem2(AGroupIntf:IOPCItemMgt;AItemServerHandle:OPCHandle;out AQuality:Word):OLEVariant;var  vErrors:PResultList;  vOPCSyncIO:IOPCSyncIO;  ItemValues: POPCITEMSTATEARRAY;begin  OLECheck(AGroupIntf.QueryInterface(IID_IOPCSyncIO,vOPCSyncIO));  try    OPCErrorCheck(vOPCSyncIO.Read(OPC_DS_DEVICE,1,@AItemServerHandle,ItemValues,vErrors));    try      OPCResultErrorsCheck(1,nil,null,vErrors);      Result:=ItemValues^[0].vDataValue;      AQuality:=ItemValues^[0].wQuality;    finally      VariantClear(ItemValues^[0].vDataValue);  //memory leak      CoTaskMemFree(ItemValues);    end;  finally    vOPCSyncIO:=nil;  end;end;