Edge cases in IsNumeric- is this overthinking it - vba

Question

I have code which looks like this:
Select Case IsNumeric(somevariable)
Case True
Resume Next
Case False
Call notnum
Else
Call MyErrorHandler
End Select
Is this overthinking it? Is there a chance IsNumeric will return something other than True or False here or is this bad programming practice?

Answer 1

Don't need the else as it will be true or false however, just a note the Else should be Case Else (moot point though as you are about to delete it)
Based on this though I wouldn't use a case for only 2 options:
If IsNumeric(somevariable) then
Resume Next
Else
Call MyErrorHandler
End if
Edit: Here is how error checking works:
Sub SheetError()
Dim MySheet As String
On Error GoTo ErrorCheck
MySheet = ActiveSheet.name
Sheets.Add
ActiveSheet.name = MySheet
MsgBox "I continued the code"
ActiveSheet.name = "XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX"
MsgBox "I will never get to here in the code"
End
ErrorCheck:
If Err.Description = "Cannot rename a sheet to the same name as another sheet, a referenced object library or a workbook referenced by Visual Basic." Then
Resume Next
Else
MsgBox "Error I am not designed to deal with"
End If
End Sub
Copy and paste this module to your personal workbook or to a new workbook and run it, step through line by line using F8 to see how it is actually dealing with the error.

Answer 2

From OP's comment I'm not using my error handler. I want to do stuff with the hopefully numeric output
Sub demo()
Dim inputs As Variant
inputs = InputBox("Prompt", "Title", "Default")
If Not IsNumeric(inputs) Then
notnum
Else
' Do what you want with numeric input inside the Else
End If
' Maybe do more stuff irrespective of input
End Sub
Sub notnum()
' do not numeric stuff here
End Sub
Or if you want to keep prompting for numeric input until the users gets it right or cancels
Sub demo2()
Dim inputs As Variant
Do
inputs = InputBox("Enter something Numeric", "Title", "Default")
Loop Until IsNumeric(inputs) Or inputs = vbNullString
If Not inputs = vbNullString Then
' Do wht you want with numeric input inside the Else
End If
' Maybe do more stuff irrespective of input
End Sub

Answer 3

Input box can have different type of input validation. Try this
something = Application.InputBox("Pls Insert the Number", Type:=1)
If something = False Then Exit Sub
'Type:=0 A formula
'Type:=1 A number
'Type:=2 Text (a string)
'Type:=4 A logical value (True or False)
'Type:=8 A cell reference, as a Range object
'Type:=16 An error value, such as #N/A
'Type:=64 An array of values