IT-Stuffs

How to Generate a Random Password or Verification String

- In some cases we need to generate the random string using the some of the input from the user. This post simply explains about the generating the Random Verification string.

- To generate the random verification string we need to give the input for how many characters we need a output, input Letter (e.g., User Name) and the number for mixing to the string.

- Use the following Random generator code class library we can create the verification codes.

''' <summary>
''' GENERATES A RANDOM STRING OF LETTERS AND NUMBERS. LETTERS CAN BE RANDOMLY 
'CAPITAL OR SMALL.
''' </summary>
''' <returns type="String">RETURNS THE RANDOMLY GENERATED KEY</returns>

Public Function Generate() As String
Dim i_key As Integer
Dim Random1 As Single
Dim arrIndex As Int16
Dim sb As New StringBuilder
Dim RandomLetter As String

' CONVERT LettersArray & NumbersArray TO CHARACTR ARRAYS
LettersArray = Key_Letters.ToCharArray
NumbersArray = Key_Numbers.ToCharArray

For i_key = 1 To Key_Chars
Randomize()
Random1 = Rnd()
arrIndex = -1
' IF THE VALUE IS AN EVEN NUMBER WE GENERATE A LETTER, OTHERWISE WE 
' GENERATE A NUMBER 
' THE NUMBER '111' WAS RANDOMLY CHOSEN. ANY NUMBER WILL DO, WE JUST NEED 
' TO BRING THE VALUE ABOVE '0' 

If (CType(Random1 * 111, Integer)) Mod 2 = 0 Then
' GENERATE A RANDOM LOCATION IN THE LETTERS CHARACTER ARRAY 
Do While arrIndex < 0
arrIndex = Convert.ToInt16(LettersArray.GetUpperBound(0) * Random1)
Loop
RandomLetter = LettersArray(arrIndex)
' CREATE ANOTHER RANDOM NUMBER. IF IT IS ODD, WE CAPITALIZE THE 
' LETTER 
If (CType(arrIndex * Random1 * 99, Integer)) Mod 2 <> 0 Then
RandomLetter = LettersArray(arrIndex).ToString
RandomLetter = RandomLetter.ToUpper
End If
sb.Append(RandomLetter)
Else
' GENERATE A RANDOM LOCATION IN THE NUMBERS CHARACTER ARRAY 
Do While arrIndex < 0
arrIndex = Convert.ToInt16(NumbersArray.GetUpperBound(0) * Random1)
Loop
sb.Append(NumbersArray(arrIndex))
End If
Next
Return sb.ToString
End Function

- To add the Reference of the dll to another project (Window or Web) and create teh object for the class RandomKeyGenerator and call the method Generate().
E.g.

protected void Button1_Click(object sender, EventArgs e)
{
RandomKeyGenerator Rnd = new RandomKeyGenerator();
Rnd.KeyChars = 5;
Rnd.KeyLetters = "Siva";
Rnd.KeyNumbers = "12345";
Response.Write(Rnd.Generate());
}

To use the namespace using RandomKey;

-> To download Random Verification String Generator Click Here

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Working With Session

- How to Check the Session expires in the main page, the redirect to the default page or login page.
- In Default.aspx page To add a label with the text “Your Name” , Text Box and Button Control with text “Go”



- To set the Session for the Name which you gave, use the following code

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
If (Trim(TextBox1.Text) <> "") Then
Session("UserName") = UCase(Trim(TextBox1.Text))
Response.Redirect("Mainpage.aspx")
Else
Response.Write("User Name Required!")
End If
End Sub

To check session expires and the other pages redirect to default page
- We can check using the Query String from the other pages to the Default Page in the Page load event.

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
If (Not IsPostBack) Then
If (Request.QueryString("session") = "expired") Then
Response.Write("Your Session has Expired")
End If
End If
End Sub

To Validate the Session in other page

Protected Sub Page_Load(ByVal sender As Object, ByVal e As 
System.EventArgs) Handles Me.Load
If (Not IsPostBack) Then
If (Session.Item("UserName") <> Nothing) Then
Label1.Text = "Welcome Dear " & 
Session.Item("UserName").ToString()
ElseIf (Session.IsNewSession = True) Then
Response.Redirect("Default.aspx?Session=expired")
Else
Response.Redirect("Default.aspx?Session=Empty")
End If
End If
' Response.Write("Session Time out:-" & 
' *Session.Timeout.ToString())
End Sub

- To Make the Session Expiry the Session.Abandon() Method is used. This Will act like Logout.

- To Set the Session Timeout duration using the web config file’s SessionState Tag.

E.g.
<sessionState mode="InProc" timeout="10">
</sessionState>

- To Use this we can set the State to Handling the Session. Normally in a small Web Application we can use the InProc mode. Other Session Modes are StateServer,SQLServer,Off,Custom.

- The Default Session Timeout Time span is 20 minutes. We can Set the Session time out maximum of 1 year i.e, 525,601 minutes.

To Set the Session Expiry in Local IIS

- If we are using the Local IIS as web server we can set the Session expiry time through the Application Pool of the IIS.

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>> We can get the COM port list available in the local system using the Name space System.Management.

>> The Serial port class's GetPortNames() method is used to get the COM Ports alone.
Eg.

String[] COMS =System.IO.Ports.SerialPort.GetPortNames();

>> We need to list the all the Ports available in the Local System then the ManagementObjectSearcher Class used.
Eg.

    ManagementObjectSearcher ObjUsbSearcher = new ManagementObjectSearcher("Select * from WIN32_SerialPort");

>> The bellow code is Navigate through the ObjUsbSearcher

foreach(ManagementObject Port1 in ObjUsbSearcher.Get())
            {
                listBox1.Items.Add((String)Port1.GetPropertyValue("Name"));
                
            }

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To place a singe button(Button1),textbox(txtViewer) in the Form and create teh new user defind method called OnClick() and wireup the event using the bellow code part

//The Default Form1() initializer Method
        public Form1()
        {
            InitializeComponent();
            button1.Click += new EventHandler(OnClick);// Onclick Based
            this.Resize+=new EventHandler(this.ResizeForm); //While Form is Resized 
        }

        // User defind method wireupped with Button1 Click
        public void OnClick(object sender, EventArgs e)
        {
            this.txtViewer.Text = "This is test for Event";
        }

        //User defind method wired with form resize 
        private void ResizeForm(object sender, EventArgs e)
        {
            MessageBox.Show("Oops! Form Resized");
        }

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To Use the bellow Method we can get the Sheets Names in the List Box(i.e, lstSheetName) availble in the Form.

public string GetExcelSheetName(String xlsName)
        {
            OleDbConnection ObjCon = null;
            DataTable ObjTable = null;
            String ConStr = String.Empty;

            try
            {
                ConStr = "Provider=Microsoft.Jet.Oledb.4.0;Data source=" +    XlsFileName;
                ConStr += ";Extended Properties=Excel 8.0;";
                ObjCon = new OleDbConnection(ConStr);
                ObjCon.Open();
                ObjTable = ObjCon.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
                if (ObjTable != null)
                {
                    String[] Sheets = new String[ObjTable.Rows.Count];
                    int i = 0;
                    foreach (DataRow dr in ObjTable.Rows)
                    {
                        Sheets[i] = dr["TABLE_NAME"].ToString();
                        i++;
                    }
                   // This List box Used to List Sheet Names in Given Excel File
                    lstSheetName.Items.AddRange(Sheets);
                    bflg = true;
                    return "Sheet Name Retrieved Successfuly.";
                }
                else
                {
                    bflg =false;
                    return "Excel Database is Empty!.";
                }
            }
            catch (Exception ex)
            {
                bflg = false;
                return ex.Message;
            }
        }

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