As you know, ASP.Net has bunch of useful validation controls and they realy make our project so easy in terms of validations. But ASP.Net doesn't have any control to validate a check box !
There are lots of way to validate a check box and here you will find out some of them.
Solution
<script runat="server" language="vbscript">
Sub CustomValidator1_ServerValidate(ByVal source As Object, ByVal args As ServerValidateEventArgs)
args.IsValid = (Privacy1.Checked = True)
End Sub
Sub ValidateCheckBox()
If CheckBox1.Checked = False Then
Label1.Visible = True
Else
Label1.Visible = False
'here is your function that you want to run after the checkbox is checked !
End If
End Sub
</script>
<div>
<asp:CheckBox ID="Privacy1" runat="server" />
<br /><br />
<asp:CustomValidator ID="CustomValidator1" runat="server" OnServerValidate="CustomValidator1_ServerValidate">Please Check The Checkbox First !</asp:CustomValidator>
<br /><br />
<asp:Button ID="Button1" runat="server" Text="Button" /></div>
<br /><br />
<div>
<asp:CheckBox ID="CheckBox1" runat="server" /><br /><br />
<asp:Label ID="Label1" runat="server" style="color: Red;" Visible="false" Text="Please Check The Checkbox First !" />
<br /><br />
<asp:Button ID="Button2" CausesValidation="false" OnClick="ValidateCheckBox" runat="server" Text="Button" />
</div>
That's it ! Now you have two kinds of CheckBox RequiredFieldValidator. When you run the page and click one of the buttons, you will see that the checkbox will have a Required Field Validator. We can do that via Custon Validator Control on ASP.Net 3.5 Toolbar on the first examples and on the second one we are able to that manually !
I hope It helps :)