Visual Basic

Here's some code that might give you an idea, since it takes a string, iterates through character by character, and tests each character.  Obviously your test will be different, but it should get you on the right track.  Taken from <a href="http://msdn.microsoft.com/en-us/library/system.string.chars.aspx">MSDN</a>[<a href="http://msdn.microsoft.com/en-us/library/system.string.chars.aspx" target="_blank" title="New Window">^</a>].

<pre lang="vb">Console.Write("Type a string : ")
Dim myString As String = Console.ReadLine()
Dim i As Integer
For i = 0 To myString.Length - 1
   If Uri.IsHexDigit(myString.Chars(i)) Then
      Console.WriteLine("{0} is a hexadecimal digit.", myString.Chars(i))
   Else
      Console.WriteLine("{0} is not a hexadecimal digit.", myString.Chars(i))
   End If
Next
' The example produces output like the following:
'    Type a string : 3f5EaZ
'    3 is a hexadecimal digit.
'    f is a hexadecimal digit.
'    5 is a hexadecimal digit.
'    E is a hexadecimal digit.
'    a is a hexadecimal digit.
'    Z is not a hexadecimal digit.  </pre>

alirezamansoori wrote:

apples

alirezamansoori wrote:

trace