Call a code behind function form Html Source code

Hey
I want to call a function present in code behind from front page (html : source code)
i want to use like this:
Source code

<a href='<%# linkAlpha("B").ToString()) %>' title="B" id="B_List" runat = "server">B</a>
Code Behind

protected string linkAlpha(string value)
    {
        //  /market-research/<%#Eval("customname")%>/

        string str = "";

        if (Request.Url.DnsSafeHost == "localhost")
        {         // /market-reports/<%# Eval("customname")%>/
            s ...