How to get CheckBoxList checked items in asp.net

asp.net checkboxlist checked items
CheckBoxList is an asp.net list web server control. checkboxlist render a multi selection check box group on a web page which allow users to select multiple items at a time. we can get the checkboxlist selected (checked) items programmatically by using its SelectedIndexChanged event. we also can display users selected items list on web page.

To do this, first we need to write an event handler for checkboxlist SelectedIndexChanged event. when users select or deselect an item from checkboxlist then the SelectedIndexChanged event fire. after the event occurs, we apply a linq query to get a list of only selected items. next we loop through the selected items collection and display the items in a label control.

The following asp.net c# example code demonstrate us how can we display checkboxlist checked items in a web page in an asp.net application.
checkboxlist-checked-items.aspx 

<%@ Page Language="C#" AutoEventWireup="true"%>    
      
<!DOCTYPE html>
        
<script runat="server">
    protected void Page_Load(object sender, EventArgs e)
    { 
        if(!Page.IsPostBack)
        {
            string[] birds = { 
                                 "Ringed Plover",
                                 "Kentish Plover",
                                 "Pheasant-tailed Jacana",
                                 "American Woodcock",
                                 "Hudsonian Godwit",
                                 "Bar-tailed Godwit"
                             };

            CheckBoxList1.DataSource = birds;
            CheckBoxList1.DataBind();
        }
    }
    protected void CheckBoxList1_SelectedIndexChanged(object sender, EventArgs e)
    {
        var items = from ListItem li in CheckBoxList1.Items
                    where li.Selected == true
                    select li;

        Label1.Text = "you checked item(s).....<br />";

        foreach (ListItem li in items)
        {
            Label1.Text += li.Text + " | " + li.Value + "<br />";
        }
    }
</script>        
        
<html xmlns="http://www.w3.org/1999/xhtml">        
<head id="Head1" runat="server">        
    <title>asp.net checkboxlist checked items</title>
</head>        
<body>        
    <form id="form1" runat="server">        
    <div>        
        <h2 style="color:MidnightBlue; font-style:italic;">        
            asp.net example - checkboxlist checked items
        </h2>        
        <hr width="550" align="left" color="Gainsboro" />        
        <asp:Label       
            ID="Label1"       
            runat="server"      
            Text="check item(s) from checkboxlist."
            Font-Size="Medium"
            Width="350"
            >      
        </asp:Label>      
        <br /><br />
        <div class="block">
            <asp:CheckBoxList 
                ID="CheckBoxList1"
                runat="server"
                RepeatLayout="Table"
                RepeatColumns="2"
                AutoPostBack="true"
                OnSelectedIndexChanged="CheckBoxList1_SelectedIndexChanged"
                >
            </asp:CheckBoxList>  
        </div>
    </div>        
    </form>        
</body>        
</html>
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