Vbscript type mismatch error apparently not justifiable

问题

I'm trying to figure out why I would get this error for the code below. I've searched on the web for possible causes but I couldn't find. Please have a look:

Dim descr, code

If WScript.Arguments.Count = 0 Then
    Set objShell = CreateObject("Shell.Application")
    objShell.ShellExecute "wscript.exe", Chr(34) & Script.ScriptFullName Chr(34) & " Run", , "runas", 1
Else
    descr = InputBox("restore point description","Crepo")
    If (descr) Then
        code = GetObject("winmgmts:\\.root default:Systemrestore").CreateRestorePoint (descr, 0, 100)
        If (code) Then
            Msgbox "System Restore Point not created (" & code & ") !", 48, "Crepo"
        Else
            Msgbox "System Restore Point successfully created", 64, "Crepo"
        End If
    End If
End If

At runtime, if I input anything, i.e. qwerty I get this error:
Line: 8
Char: 2
Error: Type mismatch: '[string: "qwerty"]'
Code: 800A000D From my researches, return type of InputBox is string and CreateRestorePoint first argument is also string. In fact, it works if I call InputBox directly as the argument.

回答1:

Instead of If (descr) Then try If (Not IsNull(descr)) Then. You ~~may~~ also want to check for empty strings too: If (Not IsNull(descr) and descr <> "") Then. In fact, as pointed out in the other answer, since the VBScript InputBox function docs note that If the user clicks Cancel, the function returns a zero-length string ("") you definitely need to check for an empty/zero-length string.

回答2:

The If clause needs a boolean (not a string):

>> descr = "qwerty"
>> If (descr) Then WScript.Echo "nonsense"
>>
Error Number:       13
Error Description:  Type mismatch

InputBox returns a string or an empty value (see here), but never Null.

来源：https://stackoverflow.com/questions/33350841/vbscript-type-mismatch-error-apparently-not-justifiable

标签

vbscript