Dim Shared As String lookUp(256)
For cadena As Integer = 0 To 256
    lookUp(cadena) = "%" + Hex(cadena)
Next cadena

Function string2url(cadena As String) As String
    Dim As String cadTemp, cadDevu
    For j As Integer = 1 To Len(cadena)
        cadTemp = Mid(cadena, j, 1)
        If Instr( "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz", cadTemp) Then
            cadDevu &= cadTemp
        Else
            cadDevu &= lookUp(Asc(cadTemp))
        End If
    Next j
    Return cadDevu
End Function

Dim As String URL = "http://foo bar/"

Print "Supplied URL '"; URL; "'"
Print "URL encoding '"; string2url(URL); "'"
Sleep