How to validate multiple CheckBox control in ASP.NET

Hi,

Most probably you wil find your answer on the following link :::

http://weblogs.asp.net/samirgeorge/archive/2009/05/02/checkboxlist-client-side-validation-using-jquery.aspx

try this it is working for me

using System;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class _Default : System.Web.UI.Page
{
    int c = 0;
    protected void Page_Load(object sender, EventArgs e)
    {
        lblMsg.Visible = false;
    }
    protected void CheckBox1_CheckedChanged(object sender, EventArgs e)
    {
      
    }
    protected void Button1_Click(object sender, EventArgs e)
    {
        foreach (Control chkcontrol in form1.Controls)
        {
            if (chkcontrol.GetType().ToString() == "System.Web.UI.WebControls.CheckBox")
            {
                if (((CheckBox)chkcontrol).Checked == true)
                {
                   
                    c++;
                    // write code when check box checked
                }
                else
                {
                    if (c == 0)
                   {
                        lblMsg.Visible = true;
                        lblMsg.Text = "please select CheckBox";
                  }
                }
            }
           
        }


    }
}

hey

most probably we uses javascript for this but there are couple of ways, use this if you wish via javascript:

 type="text/javascript">

    $('table[id$=GridView1]').find('input:checkbox').click(function(e) {
        var tr = $(this).closest('tr');
        var lblError = tr.find('span[id$=lblError]');
        if (tr.find('input:checkbox:checked').length == 3) {
            lblError.html('Not possible to select more than 2.');
            this.checked = false;
        }
        else {

            lblError.html('');
        }
    });

visit there for more:

http://wikiaspnet.wordpress.com/2008/08/22/validate-checkbox/