.aspx代码如下：
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Sample 3-04 05.aspx.cs" Inherits="Sample_3_1" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<link href="StyleSheet.css" rel="stylesheet" type="text/css" />
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div id="mydiv" runat="server" >
<h2>单选按钮应用例程</h2>
<p>三个毫无关联的RadioButton: </p>
<asp:RadioButton ID="rb_1" runat="server" Text="单枪匹马1" />
<asp:RadioButton ID="rb_2" runat="server" Text="单枪匹马2" />
<asp:RadioButton ID="rb_3" runat="server" Text="单枪匹马3" />
<hr />
<p>拥有相同GroupName属性的Button </p>
<asp:RadioButton ID="rb_a1" runat="server" Text="猫" GroupName="animal" />
<asp:RadioButton ID="rb_a2" runat="server" Text="狗" GroupName="animal"
/>
<asp:RadioButton ID="rb_a3" runat="server" Text="猪" GroupName="animal" />
<asp:RadioButton ID="rb_a4" runat="server" Text="羊" GroupName="animal" />
<br /> <br />
通过按钮测试选中的动物：<br /><br />
<asp:Button ID="Button1" runat="server" Text="选中什么动物？"
οnclick="Button1_Click" /><asp:TextBox ID="txt_animal" runat="server"></asp:TextBox>
<hr />
通过后台程序来操控被选中的按钮： <br /><br />
请输入一个0-120之间的数：
<asp:TextBox ID="txt_nums" runat="server"></asp:TextBox>
<asp:Button ID="btn_checknum" runat="server" Text="确定"
οnclick="btn_checknum_Click" /> <br />
<asp:Label ID="lab_info" runat="server" ForeColor="Red" ></asp:Label> <br /><br />
<asp:RadioButton ID="rb_num1" runat="server" GroupName="numcheck" Text="不及格" />
<asp:RadioButton ID="rb_num2" runat="server" GroupName="numcheck" Text="合格" />
<asp:RadioButton ID="rb_num3" runat="server" GroupName="numcheck" Text="良好" />
<asp:RadioButton ID="rb_num4" runat="server" GroupName="numcheck" Text="优秀" />
</div>
</form>
</body>
</html>
.aspx.cs代码如下：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class Sample_3_1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
if (rb_a1.Checked) { txt_animal.Text = "您选中了:" + rb_a1.Text; }
if (rb_a2.Checked) { txt_animal.Text = "您选中了:" + rb_a2.Text; }
if (rb_a3.Checked) { txt_animal.Text = "您选中了:" + rb_a3.Text; }
if (rb_a4.Checked) { txt_animal.Text = "您选中了:" + rb_a4.Text; }
/*
* 采用控件遍历的方法，寻找GroupName为animal的RadioButton，
* 了解有这种方法，并知道有foreach这种循环
//定义一个变量，类型为控件：RadioButton
RadioButton myrb;
foreach (Control ctl in mydiv.Controls ) { //遍历mydiv下的所有控件，每一次循环都将控件赋值给名为ctl的控件变量进行操作
//判断是否为RadioButton类型的控件
if (ctl is RadioButton) {
//将控件转为RadioButton类进行操作
myrb = (RadioButton)ctl;
if (myrb.GroupName == "animal" && myrb.Checked) //如果groupnamd为animal并且是选中状态的，那么输出
{ txt_animal.Text = "您选中的动物是:" + myrb.Text; }
}
}
*/
}
protected void btn_checknum_Click(object sender, EventArgs e)
{
double d_num=-1;
//清空动作 必须有：否则页面会保留最后一次的选中结果，而使得程序设置语句无效
rb_num1.Checked = false;
rb_num2.Checked = false;
rb_num3.Checked = false;
rb_num4.Checked = false;
//和d_num=-1，及第一个逻辑表达式协同工作，规避输入错误
//此语句中，作为数字可以复制给d_num的，将正确赋值； 而例如文字等不能赋值给d_num的，就会跳过不执行，
//此时仍然：d_num=-1,
try { d_num = double.Parse(txt_nums.Text);}
catch { }
//到这里， d_num必然是一个数字
if (d_num < 0 || d_num > 120)
{
lab_info.Text = "请输入正确的数字";
}
else {
lab_info.Text = "";
if (d_num < 60) { rb_num1.Checked = true; }
if (d_num >= 60 && d_num < 80) { rb_num2.Checked = true; }
if (d_num >= 80 && d_num < 100) { rb_num3.Checked = true; }
if (d_num >= 100 && d_num <= 120) { rb_num4.Checked = true; }
}
}
}
效果如下：
