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Generate One Time Password (OTP) in Asp.net using C#, VB.NET

Aug 27, 2015
Introduction

Here I will explain how to generate random one time password or otp in
asp.net using c#, vb.net with example or generate unique random otp or one time password in asp.net using c#, vb.net with example or generate random alphanumeric one time password or otp in asp.net using c#, vb.net with example.

Description:
  
In previous articles I explained insert, update, delete in gridview with single stored procedure, jQuery gridview crud operations without postback in asp.net,
gridview examples in asp.net, display images from database using handler in asp.net, generate random password in asp.net using c# and many articles relating to gridview, asp.net, c#,vb.net and jQuery. Now I will explain how to generate random alphanumeric otp or one time password in asp.net using c#, vb.net with example.

To generate random otp in asp.net open your aspx page and write the following code


<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Generate Random Number or String or Password in Asp.net</title>
</head>
<body>
<form id="form1" runat="server">
<div>
Enter Number of Characters: <asp:TextBox ID="txtCharacters" runat="server"/>
<asp:Button ID="btnGenerate" Text="Generate" runat="server"
onclick="btnGenerate_Click" /><br />
<asp:Label ID="lblResult" runat="server" ForeColor="Red" />
</div>
</form>
</body>
</html>

Now add following namespaces in code behind

C# Code


using System;
using System.Web;

After completion of adding namespaces you need to write the code like as shown below


protected void Page_Load(object sender, EventArgs e)
{

}
protected void btnGenerate_Click(object sender, EventArgs e)
{
// declare array string to generate random string with combination of small,capital letters and numbers
char[] charArr = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray();
string strrandom = string.Empty;
Random objran = new Random();
int noofcharacters = Convert.ToInt32(txtCharacters.Text);
for (int i = 0; i < noofcharacters; i++)
{
//It will not allow Repetation of Characters
int pos = objran.Next(1, charArr.Length);
if (!strrandom.Contains(charArr.GetValue(pos).ToString()))
strrandom += charArr.GetValue(pos);
else
i--;
}
lblResult.Text = strrandom;
}

VB.NET Code


Imports System.Web
Partial Class VBCode
Inherits System.Web.UI.Page
Protected Sub Page_Load(sender As Object, e As EventArgs)

End Sub
Protected Sub btnGenerate_Click(ByVal sender As Object, ByVal e As EventArgs)
' declare array string to generate random string with combination of small,capital letters and numbers
Dim charArr As Char() = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ".ToCharArray()
Dim strrandom As String = String.Empty
Dim objran As New Random()
Dim noofcharacters As Integer = Convert.ToInt32(txtCharacters.Text)
For i As Integer = 0 To noofcharacters - 1
'It will not allow Repetation of Characters
Dim pos As Integer = objran.[Next](1, charArr.Length)
If Not strrandom.Contains(charArr.GetValue(pos).ToString()) Then
strrandom += charArr.GetValue(pos)
Else
i -= 1
End If
Next
lblResult.Text = strrandom
End Sub
End Class

Demo

Generate One Time Password (OTP) in Asp.net using C#, VB.NET

Download Sample Code Attached


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4 comments :

Bhushan Gupta said...

It's otp generation sample ?

Anonymous said...

it is not working for 99,568 etc etc

Suresh Dasari said...

@bhushan yes it's otp generation sample only based on your requirement you need to change charArr arrray...

Suresh Dasari said...

If you want only numbers please change charArr array mention only numbers

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