HOW TO CREATE A CAPTCHA IN FORM USING C#
Registration.aspx
Registration.aspx.cs
GenerateCaptcha.aspx.cs
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Registration.aspx.cs" Inherits="Registration"
%>
<!DOCTYPE html PUBLIC "-//W3C//DTD
XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="SM1" runat="server">
</asp:ScriptManager>
<table style="border: solid 1px black; padding: 20px; position: relative; top: 50px;"
align="center">
<tr>
<td>
Email ID :
</td>
<td>
<asp:TextBox ID="txtEmailID" runat="server" Width="200px"></asp:TextBox>
</td>
</tr>
<tr>
<td>
Password :
</td>
<td>
<asp:TextBox ID="txtPassword" runat="server" TextMode="Password" Width="200px"></asp:TextBox>
</td>
</tr>
<tr>
<td>
Confirm Password :
</td>
<td>
<asp:TextBox ID="txtConfirmPassword" runat="server"
TextMode="Password"
Width="200px"></asp:TextBox>
</td>
</tr>
<tr>
<td>
Enter Below Code :
</td>
<td>
<asp:TextBox ID="txtCaptcha" runat="server" Width="200px"></asp:TextBox>
</td>
</tr>
<tr>
<td>
</td>
<td valign="middle">
<asp:UpdatePanel ID="UP1" runat="server">
<ContentTemplate>
<table>
<tr>
<td style="height: 50px; width:100px;">
<asp:Image ID="imgCaptcha" runat="server" />
</td>
<td valign="middle">
<asp:Button ID="btnRefresh"
runat="server"
Text="Refresh"
OnClick="btnRefresh_Click"
/>
</td>
</tr>
</table>
</ContentTemplate>
</asp:UpdatePanel>
</td>
</tr>
<tr>
<td colspan="2" align="center">
<asp:Button ID="btnRegiser" runat="server" Text="Register" OnClick="btnRegister_Click" />
</td>
</tr>
</table>
</div>
</form>
</body>
</html>
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Web;
using
System.Web.UI;
using
System.Web.UI.WebControls;
using
System.Text;
public partial class Registration : System.Web.UI.Page
{
protected void Page_Load(object
sender, EventArgs e)
{
if
(!IsPostBack)
{
FillCapctha();
}
}
void
FillCapctha()
{
try
{
Random
random = new Random();
string
combination = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
StringBuilder
captcha = new StringBuilder();
for
(int i = 0; i < 6; i++)
captcha.Append(combination[random.Next(combination.Length)]);
Session["captcha"]
= captcha.ToString();
imgCaptcha.ImageUrl = "GenerateCaptcha.aspx?" + DateTime.Now.Ticks.ToString();
}
catch
{
throw;
}
}
protected void btnRefresh_Click(object
sender, EventArgs e)
{
FillCapctha();
}
protected void btnRegister_Click(object
sender, EventArgs e)
{
if
(Session["captcha"].ToString() !=
txtCaptcha.Text)
Response.Write("Invalid Captcha Code");
else
Response.Write("Valid Captcha Code");
FillCapctha();
}
}
using
System;
using
System.Collections.Generic;
using
System.Linq;
using
System.Web;
using
System.Web.UI;
using
System.Web.UI.WebControls;
using
System.Drawing;
using System.Drawing.Drawing2D;
using
System.Drawing.Imaging;
public partial class GenerateCaptcha : System.Web.UI.Page
{
protected void Page_Load(object
sender, EventArgs e)
{
Response.Clear();
int
height = 30;
int
width = 100;
Bitmap
bmp = new Bitmap(width,
height);
RectangleF
rectf = new RectangleF(10,
5, 0, 0);
Graphics
g = Graphics.FromImage(bmp);
g.Clear(Color.White);
g.SmoothingMode = SmoothingMode.AntiAlias;
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
g.DrawString(Session["captcha"].ToString(), new Font("Thaoma", 12, FontStyle.Italic),
Brushes.Green, rectf);
g.DrawRectangle(new Pen(Color.Red), 1, 1, width - 2, height - 2);
g.Flush();
Response.ContentType = "image/jpeg";
bmp.Save(Response.OutputStream, ImageFormat.Jpeg);
g.Dispose();
bmp.Dispose();
}
}
Download Source Code:captchaform