IsAlphaNumeric Function:

The IsAlphaNumeric function checks a string and allows only white space, letters of the alphabet, numbers, or underscore characters to pass as valid input.

Syntax:
boolean = IsAlphaNumeric(string)
Example Usage: 
<%
 ' IsAlphaNumeric returns True
response.write IsAlphaNumeric("This Thing")
response.write IsAlphaNumeric("This_Thing 155088_45515")
response.write IsAlphaNumeric("Some_Other Thing_25")
response.write IsAlphaNumeric(17968)

 ' IsAlphaNumeric returns False
response.write IsAlphaNumeric("(37.8)")
response.write IsAlphaNumeric("37.8A[")
response.write IsAlphaNumeric("ABSD= acscrrrw!")
response.write IsAlphaNumeric("11200-5432")
%>
ASP Source Code: 
<%
Private Function IsAlphaNumeric(byVal string)
	dim regExp, match, i, spec
	For i = 1 to Len( string )
		spec = Mid(string, i, 1)
		Set regExp = New RegExp
		regExp.Global = True
		regExp.IgnoreCase = True
		regExp.Pattern = "[A-Z]|[a-z]|\s|[_]|[0-9]|[.]"
		set match = regExp.Execute(spec)
		If match.count = 0 then
			IsAlphaNumeric = False
			Exit Function
		End If
		Set regExp = Nothing
	Next
	IsAlphaNumeric = True
End Function
%>