[color=FF0000]using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        this.textusername.Text = "";
        this.textuserpwd.Text = "";
    }
    protected void TextBox1_TextChanged(object sender, EventArgs e)
    {

    }
    protected void TextBox2_TextChanged(object sender, EventArgs e)
    {

    }
    protected void btnLogin_Click(object sender, EventArgs e)
    {
        if (this.textusername.Text = "a"  && this.textuserpwd.Text = "a[color=00FF00]")//就是这行[/color]        {
            this.lbMessage.Text = "登入成功";
        }
        else
        {
            this.lbMessage.Text = "登入失败";
        }
    }
}[/color]


[b]为什么&&在c# 2005编译器里被看做是是运算符？而在c#2003编译器里就不会报错？我想要达到＂和＂的效果应该用什么关键字？[/b]