连接字符串以用作字段

Question

我有一个infopath数据源中的14个字段的列表，我试图循环它们以检查空格。这就是我放在一起，但它不喜欢UserInput之后的Field我会把它看起来也应该是这样的：

需要它以这种方式工作：

Private Sub ClearSpaces()
 For i As Integer = 1 To 14
   Dim DayString As String = System.Convert.ToString(i)
   Dim Field As String = "Reason" & DayString
   If String.IsNullOrEmpty(UserInput.Field.Trim()) Then
      MessageBox.Show("Day " & DayString, "OK", MessageBoxButtons.OK)
   End If
 Next
End Sub

这适用于Reason1：

Private Sub ClearSpaces()
 For i As Integer = 1 To 14
   Dim DayString As String = System.Convert.ToString(i)
   Dim Field As String = "Reason" & DayString
   If String.IsNullOrEmpty(UserInput.Reason1.Trim()) Then
      MessageBox.Show("Day " & DayString, "OK", MessageBoxButtons.OK)
   End If
 Next
End Sub