Anybody have a IsHex() function? [Resolved]

IsHex()

I will begin writing one myself, but if anyone already has one, I'd like to use it.

Thanks!

Dave

This pair of functions takes care of it. You could probably write something better...

VB Code:

Option Explicit
'
'
 
Private Function IsByteHex(char As Variant) As Boolean
    ' Checks if char is a Hexidecimal digit
    '
    IsByteHex = False
    '
    If IsNumeric(char) = True Then
        IsByteHex = True
    ElseIf char = "a" Then
        IsByteHex = True
    ElseIf char = "b" Then
        IsByteHex = True
    ElseIf char = "c" Then
        IsByteHex = True
    ElseIf char = "d" Then
        IsByteHex = True
    ElseIf char = "e" Then
        IsByteHex = True
    ElseIf char = "f" Then
        IsByteHex = True
    End If
    '
End Function
 
Public Function IsHex(strInput As String) As Boolean
    ' Checks if strInput is a Hexidecimal number
    '
    Dim i As Integer
    Dim blnIsHex As Boolean
    Dim char As Variant
    '
    IsHex = False
    blnIsHex = True
    '
    If Len(strInput) = 0 Then
        blnIsHex = False
    End If
    '
    For i = 1 To Len(strInput)
        '
        char = CVar(Mid(strInput, i, 1))
        '
        If IsByteHex(char) = True Then
            blnIsHex = (blnIsHex And True)
        Else
            blnIsHex = (blnIsHex And False)
        End If
    Next
    '
    IsHex = blnIsHex
    '
End Function

I may be too late in responding, but...

VB Code:

Public Function IsHex(strInput As String) As Boolean
  Dim i As Long
  
  IsHex = False
  
  If Len(strInput) = 0 Then Exit Function
  
  For i = 1 To Len(strInput)
    If Not (Mid$(strInput, i, 1) Like "[0-9a-hA-H]") Then Exit Function
  Next
  
  IsHex = True
End Function

optimized code:

VB Code:

Public Function IsHex(strInput As String) As Boolean
 Dim I As Long
 Dim J as Long
 
 If LenB(strInput) = 0 Then
  Exit Function
 End If
 
 I = 1
 J = Len(strInput)
 Do Until I > J
  If Not (Mid$(strInput, I, 1) Like "[0-9a-hA-H]") Then
   Exit Function
  End If
 
  I = I + 1
 Loop
 
 IsHex = True
End Function

Thanks guys, I like your functions better than mine. I never used the Like operator before...

I didn't understand this part:
" If IsNumeric(char) = True Then
IsByteHex = True
"
Just because a number contains "0" doesn't make it Hex. I.e., "20198"

20198 is valid Hex though, just because it doesn't contain any letters doesn't mean it's not Hex. The code above just tests whether a string contains only numbers and letters A through F.

Okay, yes it could be hex - lol. In my case, I have a program that tests an instrument through a serial port. It mostly responds in decimal, but every now and then it "burbs" and responds in HEX.

I had a similar For next loop to look for A-F, then I know the instrument burped, and to process the response accordingly.

I went searching to see if there was a built-in "IsHex" function (which there isn't) and found this old message string.

The bad thing is if the instrument "burps" and responds in hex, but without the A-F, I am going to get some wild data. - Hah, just ran in to that, but the program does detect Bull Shite data, well, mostly does.
I do like the "Like" statement, but for now will stick with the for next statement

These ancient threads are always recipe for disaster. You'll be better off if you don't use any code out of these without applying common sense first.

Btw, here is non-optimized straight-forward no-loop one-liner of an IsHex that might be useful to someone

Code:

---

Option Explicit

Private Sub Form_Load()
    Debug.Print IsHex("A0")
End Sub

Public Function IsHex(ByVal sText As String) As Boolean
    If LenB(sText) <> 0 Then
        IsHex = Not (sText Like "*[!0-9a-fA-F]*")
    End If
End Function

---

It's like a double negative i.e. "does not contain nothing by hex digits".

cheers,
</wqw>

p.s. For decimal numbers it's similar: IsDec = Not sText Like "*[!0-9]*"