Implementing number conversion with ASP

<%
' * * * BEGIN FUNCTION Area * * *

' Formats a given digit a nice looking phone number
' Example:given Strnumber of 8005551212 for You (800) 555-1212
Function Formatphonenumber (Strnumber)
Dim strinput ' String to hold our entered number
Dim strtemp ' Temporary string to hold our working text
Dim Strcurrentchar ' Var for storing each character for Eval.
Dim I ' looping var

' Uppercase all characters for consistency
Strinput = UCase (strnumber)

' To is able to handle some pretty bad formatting we strip out
' All characters except for chars A to-Z and digits 0 to 9
' Before proceeding. I left in the chars for stupid slogan
' Numbers like 1-800-get-cash etc ...
For I = 1 to Len (strinput)
Strcurrentchar = Mid (Strinput, I, 1)
' Numbers (0 to 9)
If ASC ("0") <= ASC (STRCURRENTCHAR) and ASC (STRCURRENTCHAR) <= ASC ("9") Then
strtemp = strtemp & Strcurrentchar
End If
' Upper case Chars (A to Z)
If ASC ("A") <= ASC (STRCURRENTCHAR) and ASC (STRCURRENTCHAR) <= asc ("Z") Then
strtemp = strtemp & Strcurrentchar
End If
Next ' I

' Swap strtemp back to Strinput for next set of validation
' I also clear strtemp just for good measure!
Strinput = strtemp
strtemp = ""

' Remove leading 1 if applicable
If Len (strinput) = one and left (strinput, 1) = "1" Then
Strinput = Right (strinput, 10)
End If

' Error catch to make sure strinput is proper length
' We ' ve finished manipulating it.
If not Len (strinput) = Then
' Handle errors as you are fit. This script raises a real
' Error so can handle it like any other runtime error,
' But you could also pass an error back via the function ' s
' Return value or just display a message ... your choice!
Err.Raise 1, "Formatphonenumber function", _
"The phone number to is formatted must be a valid digit US phone number!"

' Two alternative error techniques!
' Response.Write ' <b>the phone number to is formatted must be a valid phone number!</b> "
' Response.End

' If you'd also need to check for
' This is below so don ' t overwrite it!
' strtemp = ' <b>the phone number to is formatted must be a valid phone number!</b> '
End If

' If an ' error occurred then the rest of this won ' t get processed!

"Build" the output string formatted to our liking!
' (XXX) xxx-xxxx
strtemp = "(" "
strtemp = strtemp & Left (strinput, 3) ' Area code
strtemp = strtemp & ")"
strtemp = strtemp & Mid (Strinput, 4, 3) ' Exchange
strtemp = strtemp & "-" "-"
strtemp = strtemp & Right (strinput, 4) ' 4 digit part

' Set return value '
Formatphonenumber = strtemp
End Function

' * * * END FUNCTION Area * * *
%>


<% ' Runtime Code
Dim Strnumbertoformat ' The phone number we pass to the function


' Retrieve the requested number or set it to the default
If request.querystring ("Phone_number") <> "" Then
Strnumbertoformat = Request.QueryString ("Phone_number")
Else
Strnumbertoformat = "1-800-555-1212"
End If

' We need to turn the ' if we want to trap errors.
' Otherwise the script would generate an error if the input
' Number wasn ' t correct.
On Error Resume Next
%>

<table border= "1" >
<TR>
<td>phone number before formatting:</td>
<td><%= Strnumbertoformat%></td>
</TR>
<TR>
<td>phone number after formatting:</td>
<TD>
<%
' Call ' function and output the results
Response.Write Formatphonenumber (Strnumbertoformat)

' Check for an error and display ' If one occurred
If Err.Number Then Response.Write Err.Description
%>
</TD>
</TR>
</TABLE>

<form action= "39.asp" method= "Get" >
Phone number to format: <input type= "text" name= "Phone_number" value= "<%= strnumbertoformat%>" >
<input type= "Submit" value= "Submit" >
</FORM>