By entering the verification code shown on the web page when a user sign up, the web site or application can prevent automated registrations. This reduces system loads and ensures better performance and security of web site or application. This tutorial will show you how to create the randomly generated verification code in ASP.NET 2.0 and C#.
In order to create a random verification code, we create a method called CreateRandomCode at first
public string CreateRandomCode(int codeCount)
{
string allChar = "0,1,2,3,4,5,6,7,8,9,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";
string[] allCharArray = allChar.Split(',');
string randomCode = "";
int temp = -1;
Random rand = new Random();
for (int i = 0; i < codeCount; i++)
{
if (temp != -1)
{
rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
}
int t = rand.Next(36);
if (temp != -1 && temp == t)
{
return CreateRandomCode(codeCount);
}
temp = t;
randomCode += allCharArray[t];
}
return randomCode; |
We used over 10 web hosting companies before we found Server Intellect. Their dedicated servers and add-ons were setup swiftly, in less than 24 hours. We were able to confirm our order over the phone. They respond to our inquiries within an hour. Server Intellect's customer support and assistance are the best we've ever experienced.
Then we generate verification code character string as exported image
private void CreateImage(string checkCode)
{
System.Drawing.Bitmap image = new System.Drawing.Bitmap(Convert.ToInt32(Math.Ceiling((decimal)(checkCode.Length * 14))), 22);
Graphics g = Graphics.FromImage(image);
try
{
Random random = new Random();
g.Clear(Color.AliceBlue);
for (int i = 0; i < 25; i++)
{
int x1 = random.Next(image.Width);
int x2 = random.Next(image.Width);
int y1 = random.Next(image.Height);
int y2 = random.Next(image.Height);
g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
}
Font font = new System.Drawing.Font("Comic Sans MS", 12, System.Drawing.FontStyle.Bold);
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2f, true);
g.DrawString(checkCode, font, new SolidBrush(Color.Red), 2, 2);
for (int i = 0; i < 100; i++)
{
int x = random.Next(image.Width);
int y = random.Next(image.Height);
image.SetPixel(x, y, Color.FromArgb(random.Next()));
}
g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
Response.ClearContent();
Response.ContentType = "image/Gif";
Response.BinaryWrite(ms.ToArray());
}
finally
{
g.Dispose();
image.Dispose();
} |
We are using Server Intellect and have found that by far, they are the most friendly, responsive, and knowledgeable support team we've ever dealt with!
Transfer function on Page_load
protected void Page_Load(object sender, EventArgs e)
{
string checkCode = this.CreateRandomCode(6);
Session["CheckCode"] = checkCode;
CreateImage(checkCode);
}
|
Looking for the VB.NET 2005 Version? Click Here!
Looking for more ASP.NET Tutorials? Click Here!
|