关于C# asp.net 验证问题 - .NET技术 / ASP.NET

[align=left][/align]C# code:
<form id="form1" runat="server">
<div class="div">
<h1>新用户注册</h1>
<br />新用户名:
<asp:TextBox ID="user_name" Columns="12" runat="server" CssClass="textbox1"
Width="140" MaxLength="12" ></asp:TextBox>
<br />

<br />
密　　码: <asp:TextBox ID="user_pwd" CssClass="textbox1" Columns="20" TextMode="Password" runat="server" Width="140" MaxLength="16" ></asp:TextBox>
<br />
<br />确认密码: <asp:TextBox ID="user_pwd1" CssClass="textbox1" Columns="20" TextMode="Password" runat="server" Width="140" MaxLength="16"></asp:TextBox>
<br />　　　　　　
<br />性　　别:　 <asp:RadioButton ID="RadioButton1" GroupName="face" runat="server" /> &nbsp;<img src="image/2205362b357.gif" alt="face1" width="24" height=&qu