writing < on the textbox tooltip

Well, having '<' or '>' in a Tooltip shouldn't cause any exception. As that is not going to be a part of your Request made to the server (like a textbox entry would be!)

So just go ahead and add a tooltip to the textbox.
There can be many intutive ways to alert/show user this tooltip kind of information.
Example: You can also put the textbox in a Div and have a tooltip text on hover of that div.

When I insert < and > symbols in a textbox and submit then it causes exception. But it is not a problem for me. As an alternative I am suggesting users to just enter < and > in the textbox.

So I suggest to users via tooltip that you enter & lt; and & gt; in the textbox.

But when I add such a tooltip that write & lt; instead of < and write & gt; instead of > I get the tooltip as write < instead of < and write > instead of >.

I can not put & lt; and & gt; in the tooltip. I want to be able to write in the tooltip these words & lt; and & gt; i dont want them to be rendered as < and > in the tooltip. Hope I am clear now.

Thanks

I still don't entirely understand your problem...

However, if you want to display the text "&lt;" instead of "<", then write "&amp;lt;" instead of "&lt;"