Dim stringa As String = "192.168.0.1" Dim isValidAddress As Boolean = False Dim _regex As Regex = New Regex("\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b") If _regex.Match(stringa).Success Then isValidAddress = True Else isValidAddress = False End If ' isValidAddress = true means that the sequence is correct If isValidAddress = True Then Dim _ipAddress As System.Net.IPAddress = Nothing isValidAddress = System.Net.IPAddress.TryParse(IPPubblicoTextBox.Text, stringa) End If ' isIPAddress = true means that the sequence is really an IP Address '********************************************************** Function EmailAddressChecker(ByVal emailAddress As String) As Boolean 'La stringa vuole SOLO caratteri Maiuscoli Dim regExPattern As String = "^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}$" 'Questa accetta maiuscoli e minuscoli regExPattern = "^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,4}$" Dim emailAddressMatch As Match = Regex.Match(emailAddress, regExPattern) If emailAddressMatch.Success Then Return True Else Return False End If End Function