Question

c#中3个combox，我怎么在选定了前面两个年、月后，最后的combox下拉框就是对应月的日期数？

Answer 1

写个判断闰年的函数，监听comboBox的selectedindexchanged事件
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Collections;

namespace WindowsFormsApplication5
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
//判断闰年
private bool checkleap(int year)
{
if ((year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0))
return true;
else
return false;
}
//绑定每月的天数

private void binddays(int year, int month)
{
int i;
ArrayList alday = new ArrayList();

switch (month)
{
case 1:
case 3:
case 5:
case 7:
case 8:
case 10:
case 12:
for (i = 1; i <= 31; i++)
alday.Add(i);
break;
case 2:
if (checkleap(year))
{
for (i = 1; i <= 29; i++)
alday.Add(i);
}
else
{
for (i = 1; i <= 28; i++)
alday.Add(i);
}
break;
case 4:
case 6:
case 9:
case 11:
for (i = 1; i <= 30; i++)
alday.Add(i);
break;

}
this.comboBox3.DataSource = alday;

}

private void Form1_Load(object sender, EventArgs e)
{
//绑定年

ArrayList alyear = new ArrayList();

int i;
for (i = 1900; i <= 2099; i++)

alyear.Add(i);

this.comboBox1.DataSource = alyear;

//绑定月

ArrayList almonth = new ArrayList();
for (i = 1; i <= 12; i++)
almonth.Add(i);

this.comboBox2.DataSource = almonth;

int year, month;
year = Int32.Parse(this.comboBox1.SelectedValue.ToString());
month = Int32.Parse(this.comboBox2.SelectedValue.ToString());
binddays(year, month);//绑定天
}

private void comboBox1_SelectedIndexChanged(object sender, EventArgs e)
{
int year, month;

year = Int32.Parse(this.comboBox1.SelectedValue.ToString());

month = 1;

binddays(year, month);
}

private void comboBox2_SelectedIndexChanged(object sender, EventArgs e)
{
int year, month;

year = Int32.Parse(this.comboBox1.SelectedValue.ToString());

month = Int32.Parse(this.comboBox2.SelectedValue.ToString());

binddays(year, month);
}
}
}

追问

为什么代码进去以后，调试后下选框里什么也没有呢？

追答

大哥，你没订阅事件好么？我这里没有手动建委托，design.cs里面有
combobox1.selectedindexchange += new 委托(函数)
你要在属性窗口里把事件都订阅了，那个闪电图标，别说你这都不知道~

Answer 2

int days = DateTime.DaysInMonth(2012, 12); //2012年12月有days天
明白怎么处理了吧？
模式：
int year =..;
int month = ..;
int days = DateTime.DaysInMonth(year , month);

追问

我开始时这样写来着，但是我怎么把我选定的前两个数据得到呢？意思我怎么把前两个combox的值转化为year和month

追答

private void cbb_Year_SelectedIndexChanged(object sender, EventArgs e)
{
cbb_day.Items.Clear();
if (cbb_month.SelectedItem!=null && cbb_month.SelectedItem.ToString() != string.Empty)
{
int year = Convert.ToInt32(cbb_Year.Text.ToString());
int month = Convert.ToInt32(cbb_month.Text.ToString());
for (int i = 0; i < DateTime.DaysInMonth(year, month); i++)
cbb_day.Items.Add((i+1).ToString());
}
}

private void cbb_month_SelectedIndexChanged(object sender, EventArgs e)
{
cbb_day.Items.Clear();
if (cbb_Year.SelectedItem!= null &&cbb_Year.SelectedItem.ToString() != string.Empty)
{
int year = Convert.ToInt32(cbb_Year.Text.ToString());
int month = Convert.ToInt32(cbb_month.Text.ToString());
for (int i = 0; i < DateTime.DaysInMonth(year, month); i++)
cbb_day.Items.Add((i + 1).ToString());
}
}

追问

不行这样在日中什么都不显示

追答

晕 你看一下日的combobox名字是不是cbb_day！
我自己测试过的代码。正常的。

Answer 3

只要通过对月份的判断就好了，

追问

不行二月是不一样的？我是初学者，能说清楚点吗？具体怎么邦定？

追答

string y=comboxY.text.tostring().trim();
int r;
if(y=="2")
r=29;
else if(y=="1" ||y=="3"||y=="5"||y="7"||y=="8"||y="10" ||y="12")
r=31;
else
r=30;
comboxR.items.clear();
for (int i=1;i<r+1;i++)
{ comboxR.items.add(i.tostring());
}
你用这段代码调试，我没在VS里测试，应该没什么大错