Question

我遇到一个小问题，关于从Excel文件中提取数据，忽略我删除某些内容的第一部分，这是因为要检索的文件是24列，其中目标文件大约是12，所以我是删除一些列。

长话短说，如果任何一行中第5列的值为“x”，我试图匹配的部分然后在同一行的第二列中写例如“E”..检查是否“X”在第6列，那么它意味着“P”应该在该行的第二列中，依此类推......

问题是，对于每个单元格，它是值“x”或者它是空的..（excel文件中没有值），所以每当代码循环遍历空元素时似乎都有问题，它抛出此错误

 l = new Microsoft.Office.Interop.Excel.Application();
 xl.Visible = false;
 Microsoft.Office.Interop.Excel.Workbook workbook = xl.Workbooks.Open(p_sUBKPath, Type.Missing, Type.Missing, 4, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);

 Microsoft.Office.Interop.Excel.Worksheet ws = (Microsoft.Office.Interop.Excel.Worksheet)workbook.Sheets[1];

 Microsoft.Office.Interop.Excel.Range range = ws.UsedRange;
 // delete columns that we don't need from the new excel file
 Microsoft.Office.Interop.Excel.Range range2 = ws.get_Range("A1","A1"); 
 range2.EntireColumn.Delete();
 Microsoft.Office.Interop.Excel.Range range3 = ws.get_Range("B1", "B1");
 range3.EntireColumn.Delete();
 Microsoft.Office.Interop.Excel.Range range4 = ws.get_Range("D1", "L1");
 range4.EntireColumn.Delete();
 Microsoft.Office.Interop.Excel.Range range5 = ws.get_Range("I1", "M1");
 range5.EntireColumn.Delete();
 Microsoft.Office.Interop.Excel.Range range6 = ws.get_Range("K1", "K1");
 range6.EntireColumn.Delete();

 //insert a new column ( Category)
 Microsoft.Office.Interop.Excel.Range range7 = ws.get_Range("B1", "B1");
 range7.EntireColumn.Insert(XlInsertShiftDirection.xlShiftToRight); 

 object[,] values = (object[,])range.Value2;
 values[1, 2] = (string)"Cat.";


 for (int row = 2; row <= values.GetUpperBound(0); row++)
 {
     try
     {
          if ((!String.IsNullOrEmpty(values[row, 5].ToString())) && values[row, 5].ToString() == "x")
          {
              values[row, 2] = (string)"E";
          }
          else if ((!String.IsNullOrEmpty(values[row, 6].ToString())) && values[row, 6].ToString() == "x")
          {
              values[row, 2] = (string)"P";
          }
          else if ((!String.IsNullOrEmpty(values[row, 7].ToString())) && values[row, 7].ToString() == "x")
          {
              values[row, 2] = (string)"Phy";
          }
          else if ((!String.IsNullOrEmpty(values[row, 8].ToString())) && values[row, 8].ToString() == "x")
          {
              values[row, 2] = (string)"L";
          }
          else if ((!String.IsNullOrEmpty(values[row, 9].ToString())) && values[row, 9].ToString() == "x")
          {
              values[row, 2] = (string)"Ex";
          }
          else
              MessageBox.Show("unknow");
       }
       catch (Exception ex)
       {
          MessageBox.Show(ex.ToString());
       }
}

错误是：

System.Nullreferenceexception对象引用未设置为对象的实例

Answer 1

我会在做.tostring（）之前做一个空检查。即：

(!String.IsNullOrEmpty(values[row, 5].ToString()))

到

!(values[row, 5] == null) && (!String.IsNullOrEmpty(values[row, 5].ToString()))

在Excel C＃中循环空值时出现System.NullReferenceException

1 个答案: