Regular Expressions IP Address Validation with .net

 Regular Expressions IP Address Validation with .net

IP Address Classes:

IP addresses are categories into five classes: Class A, Class B, Class C, Class D and Class E. Each class allows for a range of valid IP addresses. whereas classes A, B and C are used to communication.

Class A Internet Protocol (IP) address ranges include 1.0.0.0 to 126.255.255.255. This class supports 16 million hosts on each of the 127 networks. network 0.0.0.0 is reserved for use as the default route and the network 127.0.0.0 is reserved for the “loopback” function.

Class B Internet Protocol (IP) address ranges include 128.1.0.0 to 191.255.255.255. This class supports 65,000 hosts on each of the 16,000 networks.

Class D Internet Protocol (IP) address ranges include 224.0.0.0 to 239.255.255.255. This class is used to support multicasting.

Class E Internet Protocol (IP) address ranges include 240.0.0.0 to 254.255.255.254. This class is used for experimentation. Class E networks have never been documented or utilized in a standard way.

IP addresses are also commonly used to divide networks into smaller ones. This concept is called subnetting. Subnet addresses include 255.0.0.0 to 255.255.255.255

Dotted-Decimal Notation

To make Internet addresses easier for people to read and write, IP addresses are often expressed as four decimal numbers, each separated by a dot. This format is called “dotted-decimal notation.” Dotted-decimal notation divides the 32-bit Internet address into four 8- bit fields and specifies the value of each field independently as a decimal number with the fields separated by dots.

Regular Expression Pattern

^(([01]?\d\d?|2[0-4]\d|25[0-5])\.){3}([01]?\d\d?|25[0-5]|2[0-4]\d)$

Imports System

Imports System.IO

Imports System.Text.RegularExpressions

Public Class Form1

    Private Sub CheckIPNumber_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles CheckIPNumber.Click

        If txtInput.Text <> "" Then

            CheckValidate(txtInput.Text)

        Else

            LblInfo.Text = "Please enter a valid IP Address"

            LblInfo.ForeColor = Color.Red

        End If

    End Sub

    Private Sub CheckValidate(ByVal strFindin As String)

        Dim myRegex As New Regex("^(([01]?\d\d?|2[0-4]\d|25[0-5])\.){3}([01]?\d\d?|25[0-5]|2[0-4]\d)$")

        If myRegex.IsMatch(strFindin) Then

            LblInfo.Text = "Valid Input"

            LblInfo.ForeColor = Color.Green

        Else

            LblInfo.Text = "Please enter a valid Ip Number"

            LblInfo.ForeColor = Color.Red

        End If

    End Sub

End Class

Using Regular Expressions

System.Text.RegularExpressions Overview 

first you need to import the library for that write following code 

Imports System.Text.RegularExpressions 

at the start of your source code.

    Sub CheckProgram()

        'The regex pattern "\d+" matches one or more digit characters together

        Dim RegularExpression As Regex = New Regex("\d+")

        Dim match As Match = RegularExpression.Match("Dot 55 Perls")

        If match.Success Then

            'If the match is successful, we print its value, which is "55".

            Console.WriteLine(match.Value)

        End If

    End Sub

 these is sample example of regular expression.

Create new dynamic button in vb.net

        

Create new dynamic button in vb.net

It’s very simple under stable code is following.

For add any control you must need assign name and location,

For label and textbox these method also work.

You also add dynamic textbox and label by use of these code

        Dim tmp As New Button

        tmp.Location = New System.Drawing.Point(30, 232)

        tmp.Name = "Demo"

        tmp.TabIndex = 4

        tmp.Text = "New Demo Button"

        tmp.Visible = True

        Me.Controls.Add(tmp)

Input decimal value in textbox in vb.net

Input decimal value in textbox in vb.net

Private previousText As String

    Sub New()

        ' This call is required by the designer.

        InitializeComponent()

        ' Add any initialization after the InitializeComponent() call.

        previousText = TextBox1.Text

    End Sub

    Private Sub TextBox1_TextChanged(sender As System.Object, e As System.EventArgs) Handles TextBox1.TextChanged

        If String.IsNullOrEmpty(DirectCast(sender, TextBox).Text) Then

            previousText = ""

        Else

            Dim num As Double = 0

            Dim success As Boolean = Double.TryParse(DirectCast(sender, TextBox).Text, num)

            If success And num >= 0 Then

                DirectCast(sender, TextBox).Text.Trim()

                previousText = DirectCast(sender, TextBox).Text

            Else

                DirectCast(sender, TextBox).Text = previousText

                DirectCast(sender, TextBox).SelectionStart = DirectCast(sender, TextBox).Text.Length

            End If

        End If

    End Sub