Excel COM对象强制转换错误

Question

我试图在代码中避免使用“双点”表示法（请参阅如何正确清理Excel互操作对象？ ）。 但是，当我尝试更改以下代码时出现错误

Excel.Workbook oWB;
...
oWB.Sheets[oWB.Sheets.Count].Delete();
oWB.Sheets[oWB.Sheets.Count].Delete();
oWB.Sheets[oWB.Sheets.Count].Delete();

对此

Excel.Sheets oS;
oS = oWB.Sheets;
//error occurs in the following line
oS = oWB.Sheets[oS.Count];
oS.Delete();
oS.Delete();
os.Delete();

错误是'Unable to cast COM object of type 'System.__ComObject' to interface type 'Microsoft.Office.Interop.Excel.Sheets'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{000208D7-0000-0000-C000-000000000046}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).' 'Unable to cast COM object of type 'System.__ComObject' to interface type 'Microsoft.Office.Interop.Excel.Sheets'. This operation failed because the QueryInterface call on the COM component for the interface with IID '{000208D7-0000-0000-C000-000000000046}' failed due to the following error: No such interface supported (Exception from HRESULT: 0x80004002 (E_NOINTERFACE)).'

任何帮助表示赞赏。

Answer 1

您必须声明一个Sheet类型的新变量。 oS的类型为Sheets ，而oS.Sheets[os.Count]的类型为Sheet （不带最终的s）。 因为从运行时的角度来看它们是不相关的类型，所以必须声明一个具有适当类型Sheet的中间变量。