In this blog, I’m explaining the concept of cookies in asp.net.

Cookies provide a way to store user-specific data. Cookies are known as many names HTTP Cookie, Response Cookie, web Cookie and Browser Cookie and more. Cookies are one of several ways to store data about web site visitors during the time when web server and browser are not connected. Cookie is small text file sent by the web server and stored by the client machine to hard disk. Cookies may be used for authentication, identification of a user session, user's preferences, shopping cart contents, or anything else that can be accomplished through storing text data. The purpose of cookie store user-specific information with in user system to reduce burden on server.

There are two major types of cookie:

·         Persistent cookie

·         Non-persistent cookie

Persistent Cookie

Cookies are stored on your computer hard disk.  They stay on your hard disk and can be accessed by web servers until they are deleted or have expired.

Non-persistent Cookie

Cookies are saved only your web browser is running. They can be used by a web server only until you close your browser.  They are not saved on your disk. A cookie has expired time expired that is Non-persistent cookie.

There are following limitations for cookies:

·    Size of cookies is limited to 4096 bytes.

·    Total 20 cookies can be used on a single website; if you exceed this browser will delete older cookies.

·    End user can stop accepting cookies by browsers, so it is recommended to check the users’ state and prompt the user to enable cookies.

Example

Step 1

Create a form as given below:

Step 2

Write the code in webForm1.aspx.cs:

using System;
using System.Web;
publicpartialclasswebForm1 : System.Web.UI.Page
{
    protectedvoid Page_Load(object sender, EventArgs e)
    {
    }
    protectedvoid btnSave_Click(object sender, EventArgs e)
    {
        HttpCookie studentObj = newHttpCookie("StudentInfo");
        studentObj["RollNumber"] = txtStudentRollNuber.Text;
        studentObj["Name"] = txtStudentName.Text;
        studentObj["Age"] = txtStudentAge.Text;
        studentObj["Country"] = ddlCountry.SelectedItem.ToString();
        studentObj["State"] = ddlState.SelectedItem.ToString();
        studentObj["City"] = ddlCity.SelectedItem.ToString();
        studentObj["Pincode"] = txtStudentPincode.Text;
        studentObj.Expires = DateTime.Now.AddMinutes(20);
        Response.Cookies.Add(studentObj);
        lblMsg.Text = "Data has been Saved";
    }
    protectedvoid btnClear_Click(object sender, EventArgs e)
    {
        txtStudentRollNuber.Text = "";
        txtStudentName.Text = "";
        txtStudentAge.Text = "";
        ddlCountry.SelectedIndex = 0;
        ddlState.SelectedIndex = 0;
        ddlCity.SelectedIndex = 0;
        txtStudentPincode.Text = "";
        lblMsg.Text = "";
    }
    protectedvoid btnRead_Click(object sender, EventArgs e)
    {
        HttpCookie readCookie = Request.Cookies["StudentInfo"];
        if (readCookie != null)
        {
            txtStudentRollNuber.Text = readCookie["RollNumber"];
            txtStudentName.Text=readCookie["Name"];
            txtStudentAge.Text=readCookie["Age"];
            ddlCountry.SelectedItem.Text = readCookie["Country"];
            ddlState.SelectedItem.Text = readCookie["State"];
            ddlCity.SelectedItem.Text = readCookie["City"];
            txtStudentPincode.Text = readCookie["Pincode"];
            lblMsg.Text = "";
        }
    }
}

Step 3

Run the application:

Fill the data and click save button.

Step 4

Click Clear button to clear.

Step 5

Click on Read button: