Why is this VBS code skipping the first condition? - vbscript

Question

The following must work in qtp so i can not use WScript.Echo. The following code have to ask for an integer between 1 to 10 inclusive using an inputbox. If nothing entered the it has to give a message "Aborted".
If anything else entered then it has to say what is the problem and ask again for the number until I abort by cancel or by entering nothing. I have the following code but it looks like it is skipping the first condition and goes to the first else in the loop:
Option Explicit
Dim vNum, sNum, nNum
Do
vNum = InputBox("Please enter an integer between 1 and 10 inclusive")
If IsEmpty(vNum) Then
msgbox("Aborted")
Exit Do
Else
sNum = Trim(vNum)
If "" = sNum Then
vNum=Inputbox("Empty string")
Else
If IsNumeric(sNum) Then
nNum = CDbl(sNum)
If nNum <> Fix(nNum) Then
vNum=inputbox("Not an Integer")
Else
If nNum < 1 Or nNum > 10 Then
vNum=inputbox ("Not in range")
Else
msgbox nNum,("number ok")
Exit Do
End If
End If
Else
vNum= inputbox ("Not a number")
End If
End If
End If
Loop
msgbox ("Done")

Answer 1

You could loop and change the instruction message each time:
Dim vNum, instruction
instruction = "Please enter an integer between 1 and 10 inclusive"
Do
vNum = InputBox(instruction)
If vNum = False Then
MsgBox "Aborted"
Exit Do
ElseIf CStr(Trim(vNum)) = "" Then
instruction = "Empty string"
ElseIf Not IsNumeric(vNum) Then
instruction = "Not an integer"
ElseIf IsNumeric(vNum) And vNum < 1 Or vNum > 10 Then
instruction = "Not in range"
ElseIf IsNumeric(vNum) And vNum > 0 And vNum < 11 Then
MsgBox "Number OK"
Exit Do
Else
instruction = "Invalid Entry"
End If
Loop

Answer 2

This is what help says.
If the user clicks OK or presses ENTER, the InputBox function returns whatever is in the text box. If the user clicks Cancel, the function returns a zero-length string ("").
So you aren't testing for a empty, or zero length, string. It is a valid string, just empty.
Also from Help the meaning of Empty in VBS, which has nothing to do with what's in a string.
Empty
The Empty keyword is used to indicate an uninitialized variable value. This is not the same thing as Null.
Update
HELP IS NOT WRONG. InputBox returns a zero length string just like the docs say.
A uninitialized variable HAS A VALUE (for numbers, dates, and strings)
0 for numbers
1899 sometime for dates
and a zero length string for strings (and a string of spaces for fixed length strings).
HELP IS NOT a TECHNICAL REFERENCE
Help is a CONTRACTUAL document describing behaviour not implementation. As in the COM philosophy.
This is known as LET COERCION. And why x=65:Msgbox x works. There are two variables there.
From VBA Implementers Guidelines
The semantics of Empty Let-coercion depend on the destination’s declared type: Source
Any numeric type - The result is 0.
Boolean - The result is False.
Date - The result is 12/30/1899 00:00:00.
String - The result is a 0-length string.
String * length - The result is a string containing length spaces.
Any class or Object - Runtime error 424 (Object required) is raised. -
Any other type except Variant - Runtime error 13 (Type mismatch) is raised.