Input Box返回值

引用：How to Detect vba InputBox "Cancel" or "X" clicked other than detecting null input ?

You need to understand the built-in function. If you cancel the input, it will return a Zero length string. The Cancel button return an empty string. There is no Args for the Cancel button. So you cannot detect the Cancel button being press by the user.

• “取消”或“X”测试是否为Null
  Sub test() On Error Resume Next Dim rng As Object rng = Application.InputBox("Select Range:", , , , , , , 8) Dim b As Boolean b=isNull(rng) MsgBox "Is Null ---" & b End Sub

不是Null

• “取消”或“X”测试是否为Nothing
  Sub test() On Error Resume Next Dim rng As Object rng = Application.InputBox("Select Range:", , , , , , , 8) Dim b As Boolean If rng Is Nothing Then b = True Else b = False End If MsgBox "Is nothing ---" & b End Sub

是Nothing

• 什么是Null，什么是Nothing
  要判断Nothing的，必须是一个对象（Object），未初始化的对象是Nothing
  Null 必须是一个变量。尚未完全理解。。。

引用：Nothing? Empty? Missing? Null?