常用网站后台与前台表单的有效性简单验证(不用验证控件，怕忘)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Text.RegularExpressions;

namespace xh.shop.web
{
public partial class reg2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{

}

protected void Button4_Click(object sender, EventArgs e)
{

}
//重置
protected void Button5_Click(object sender, EventArgs e)
{
txtanswer.Text = "";
txtemail.Text = "";
txtname.Text = "";
txtpwd.Text = "";
txtqrpwd.Text = "";
txtquestion.Text = "";
}
//返回
protected void Button6_Click(object sender, EventArgs e)
{
Response.Redirect("index.aspx");
}
//注册
protected void butcz(object sender, EventArgs e)
{
string answer = txtanswer.Text.Trim();
string email= txtemail.Text.Trim();
string name = txtname.Text.Trim();
string pwd = txtpwd.Text.Trim();
string qrpwd = txtqrpwd.Text.Trim();
string question = txtquestion.Text.Trim();
//----------------------------------------------------验证开始
//验证输入是否完整
if (answer.Length==0||email.Length==0||name.Length==0||pwd.Length==0||qrpwd.Length==0||question.Length==0)
{
Response.Write("<script language='JavaScript'>alert('输入不完整')</script>");
return;
}
//验证密码与确认密码是否一致
if (pwd!=qrpwd)
{
Response.Write("<script language='JavaScript'>alert('密码与确认密码不一致')</script>");
return;
}
//验证密码
if (!Regex.IsMatch(pwd,"^[a-zA-Z0-9]{6,20}$"))
{
Response.Write("<script language='JavaScript'>alert(' 密码长度必须大于6个字符小于20个字符，只能为英语字、数字，例如：snsn2003等')</script>");
return;
}
//验证电子邮件
if (!Regex.IsMatch(email, @"\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*"))
{
Response.Write("<script language='JavaScript'>alert('请输入有效的邮件地址')</script>");
return;
}
//验证用户名是否存在
if (new xh.shop.DAL.user().Exists(name))
{
Response.Write("<script language='JavaScript'>alert('用户名已经存在')</script>");
return;
}
//--------------------------------------------------------验证结束
int res=    new xh.shop.DAL.user().Add(new xh.shop.Model.user() {
username=name,
createdate=DateTime.Now,
answer=answer,
email=email,
password=pwd,
question=question

});
if (res > 0)
{
Response.Write("<script language='JavaScript'>alert('添加成功')</script>");
txtanswer.Text = "";
txtemail.Text = "";
txtname.Text = "";
txtpwd.Text = "";
txtqrpwd.Text = "";
txtquestion.Text = "";
}
else
{
Response.Write("<script language='JavaScript'>alert('添加失败')</script>");
return;
}
}
}
}