方法一：使用IsNullOrWhiteSpace属性 返回值为TRUE 加入！取其相反的值 using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls; public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{ }
protected void Button1_Click(object sender, EventArgs e)
{
string uname = "admin";
string upwd = "123456";
if (!string.IsNullOrWhiteSpace(this.TextBox1.Text) && !string.IsNullOrWhiteSpace(this.TextBox2.Text))
{
if (uname == this.TextBox1.Text)
{
if (upwd == this.TextBox2.Text)
{
this.TextBox1.Text = this.TextBox2.Text = "";
Label1.Text = "登录成功";
}
else
{
Label1.Text = "密码不正确";
}
}
else
{
Label1.Text = "用户名不正确";
}
}
else
{
Label1.Text = "用户名或密码未输入";
}
}
}方法二：使用 //--利用RequiredFieldValidator 这个系统自带的验证控件进行验证，需要修改controlvalidate=text1.text 修改errormessage=提示信息
