Integer.FromHex Behavior

General
1

If find it odd that the .FromHex function will return a value from a string that has non-hex characters. For example, Integer.FromHex(“Jon”) returns 5271. I don’t understand why this doesn’t throw an error.

In a project I want to enter hex bytes through a text field but need to verify them before converting and passing on to a serial device. I came up with this:

Function IsHexByte(s As String) As Boolean

s = s.Uppercase.Trim

If s.IsEmpty Or (s.Bytes > 2) Then
  Return False
End If

Var HexDigits As String = "0123456789ABCDEF"

If HexDigits.IndexOf(s.Middle(0, 1)) = -1 Then
  Return False
End If

If s.Bytes = 2 Then
  If HexDigits.IndexOf(s.Middle(1, 1)) = -1 Then
    Return False
  End If
End If

Return True

Am I missing something with .FromHex?

2

Wow! Wrong, and inconsistent, as Integer.FromString(“123a”) raises.

File a Feedback report.