CAPTCHA in WPF Using C#

Introduction

This article explains how to create a CAPTCHA in WPF using the C# and XAML . CAPTCHA is an image of random words, like afs43, ahd4kj and so on . CAPTCHA stands for "Completely Automated Public Tuning Test" that determines whether or not the user is a human being.

Many users use automated programs to block other users from registering for a PGL account. In order to stop this blockings (by an automated program) we use a CAPTCHA. It is also used to prevent bots from registering for free email accounts and email addresses.

Step 1

First we create a WPF application using the following procedure:

Open the Visual Studio.
Select "New Project".
Select the WPF Application.
Name the project "Captcha in wpf".
Click the "OK" button.

Step 2

Now we use some tools from the toolbox .

So now go to "View" -> "Toolbox".
Then Drag and Drop 1 textbox and 1 button onto the design view.

Select the TextBox and press F4 .
Change the background, font style, font weight, font size and foreground.

Step 3

After the changes, the final source code of the MainWindow.xaml is as in the following:

<Window x:Class="Ceptcha_in_WPF.MainWindow"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

Title="MainWindow" Height="350" Width="525" Background="{x:Null}">

</Grid>

</Window>

Step 4

Go to the MainWindow.xaml.cs.
Write the following code in MainWindows.xaml.cs.

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Data;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Imaging;

using System.Windows.Navigation;

using System.Windows.Shapes;

namespace Ceptcha_in_WPF

{

/// <summary>

/// Interaction logic for MainWindow.xaml

/// </summary>

public partial class MainWindow : Window

{

public MainWindow()

{

InitializeComponent();

}

private void button1_Click(object sender, RoutedEventArgs e)

{

String allowchar = " ";

allowchar = "A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";

allowchar += "a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,y,z";

allowchar += "1,2,3,4,5,6,7,8,9,0";

char [] a = {','};

String [] ar = allowchar.Split(a);

String pwd = " ";

string temp = " ";

Random r = new Random();

for (int i = 0; i < 6; i++)

{

temp = ar [(r.Next(0,ar.Length))];

pwd += temp;

}

textBox1.Text =pwd ;

}

Output

Then press F5.

Now click on the button.

3 Comments

Join the conversation! Your thoughts help the community grow.

Shalabh Saxena12y ago
very easy to learn example for beginners. Much appreciated and now I am implementing this in MVVM.
Kiran Kumar Talikoti13y ago
Thank u.Very useful :)
Rohit Maurya13y ago
can u give simple example about validation of captcha in WPF