Get Html CheckBoxes checked value in code behind using C# and VB.Net

Hi zulkarnain,

Check this example. Now please take its reference and correct your code.

HTML

<div class="ct-u-displayTableCell">
    <div class="ct-checbox--custom">
        <input type="checkbox" value="Air Condition" name="check" />
        <label for="ch1" id="">
            Air Condition
        </label>
    </div>
    <div class="ct-checbox--custom">
        <input type="checkbox" value="ADSL Cable" name="check" />
        <label for="ct-checbox--custom2">
            ADSL Cable
        </label>
        <span></span>
    </div>
    <div class="ct-checbox--custom">
        <input type="checkbox" value="WiFi" name="check" />
        <label for="ct-checbox--custom3">
            WiFi
        </label>
        <span></span>
    </div>
    <div class="ct-checbox--custom">
        <input type="checkbox" value="HiFi Audio" name="check" />
        <label for="ct-checbox--custom4">
            HiFi Audio
        </label>
    </div>
</div>
<input value="Save" type="Submit" onserverclick="GetSelectedValue" runat="server" />

C#

protected void GetSelectedValue(object sender, EventArgs e)
{
    string checkedCheckBoxes = Request.Form["check"];
    if (!string.IsNullOrEmpty(checkedCheckBoxes))
    {
        ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('Checked values are \\n\\r" + checkedCheckBoxes + "')", true);
    }
    else
    {
        ClientScript.RegisterClientScriptBlock(this.GetType(), "", "alert('Please select checkbox.')", true);
    }
}

VB.Net

Protected Sub GetSelectedValue(ByVal sender As Object, ByVal e As EventArgs)
    Dim checkedCheckBoxes As String = Request.Form("check")
    If Not String.IsNullOrEmpty(checkedCheckBoxes) Then
        ClientScript.RegisterClientScriptBlock(Me.[GetType](), "", "alert('Checked values are \n\r" & checkedCheckBoxes & "')", True)
    Else
        ClientScript.RegisterClientScriptBlock(Me.[GetType](), "", "alert('Please select checkbox.')", True)
    End If
End Sub

Screenshot

Note: When you select multiple checkboxes you will get the value with comma separated string in the Request.Form collection.