VS复习提要

MessageBox.Show("文档已经被改变，是否保存？", "提示", MessageBoxButtons.YesNo)MessageBox.Show("文档已经被改变，是否保存？", "提示", MessageBoxButtons.OkCancel)ToolStriip控件可以在窗体中设计工具栏Get访问器用于设置属性的读操作Set访问器用于设置属性的写操作现有类的定义：public class Employee，其定义构造函数的写法正确的是 public Employee(){…} string connstr = "Data Source=(local);Initial Catalog=tech;User ID=sa;Password=";此字符串中，“Data Source”项用于指定希望访问的计算机即数据库服务名称。

通过Initial Catalog关键字制定希望访问的数据库。

using System.Data.SqlClient;using System.Data;//数据库连接string connstr = "Data Source=(local);Initial Catalog=vod;User ID=vod;Password=vod"; SqlConnection sqlconn = new SqlConnection(connstr);sqlconn.Open();//执行select（或其他SQL）命令string sql = "select * from login";SqlCommand cmd = new SqlCommand(sql, sqlconn);SqlDataReader dr;dr = cmd.ExecuteReader();//读下一条记录dr.Read();//显示字段内容Console.WriteLine(dr["username"].ToString());//关闭连接sqlconn.Close();Console.Read();例如：using System;using System.Collections.Generic;using System.Text;using System.Data;using System.Data.SqlClient;namespace ConsoleApplication1{class Program{static void Main(string[] args){string connstr = "Data Source=(local);Initial Catalog=student;UserID=sa;Password=sa";SqlConnection sqlconn = new SqlConnection(connstr);sqlconn.Open(); //数据库连接string sql = "select *from studentInfo";SqlCommand cmd = new SqlCommand(sql, sqlconn);SqlDataReader dr;dr = cmd.ExecuteReader(); //执行select(或其他Sql)命令while(dr.Read()) //读下一条记录{Console.WriteLine("学号:"+dr["StuID"].ToString() +",姓名:"+dr["StuName"].ToString() +",性别:"+dr["sex"].ToString ()+",班级ID:"+dr["classID"]); //显示字段内容}Console.Read();}}}循环语句：双引号中的｛0｝必须是西文状态下的。

Environment.GetEnvironmentVariables()取系统注册的环境变量，得到的是一个集合变量。

利用for each语句将其内容显示出来。

continue的确切含义是，结束本次循环，但是并不退出循环体。

随机数的生成方法：int n;Random r = new Random();n = r.Next(3);//n即为一个随机小于3的正整数(0～2)，可以用0表示石头、1表示剪刀、2表示布猜数游戏：身份号码验证：代码如下：public partial class Form1 : Form{public Form1(){InitializeComponent();}private void button1_Click(object sender, EventArgs e){string shenfen = textBox1.Text;Console.WriteLine(shenfen.Length);if (shenfen.Length < 18){MessageBox.Show("长度不足！");textBox1.Focus();textBox1.SelectAll();return;}if(shenfen[17] <= '0'|| shenfen[17] >= '9'&& shenfen[17] != 'X'&& shenfen[17] != 'x'){MessageBox.Show("最后一位错误");textBox1.Focus();return;}for (int i = 0; i <= 16; i++){if (shenfen[i] <= '0' && shenfen[i] >= '9'){MessageBox.Show("第" + (i + 1) + "位错误！");textBox1.Focus();return;}}if (Convert.ToInt32(shenfen[16]) % 2 == 0){label2.Text = "性别：女"; }else{label2.Text = "性别：男";}}}石头剪子布游戏：代码如下：Say Hello代码如下：public partial class Form1 : Form{public Form1(){InitializeComponent();}private void btnHide_Click(object sender, EventArgs e) {if (btnHide.Text == "显示Label"){label1.Visible = true; ;btnHide.Text = "显示TextBox";textBox1.Visible = false; ;}else{label1.Visible = false; ;btnHide.Text = "显示Label";textBox1.Visible = true; ;}}}打字速度测试：相关代码如下：public partial class Form1 : Form{public Form1(){InitializeComponent();}int second = 0;private void button1_Click(object sender, EventArgs e){if (button1.Text == "计时开始"){textBox1.Enabled = true;timer1.Enabled = true;button1.Text = "计时停止";second = 0;label1.Visible = false;}else{textBox1.Enabled = false;float sudu = 0;float minute = second / 60f;timer1.Enabled = false;sudu = textBox1.Text.Length / minute;label1.Text = "您的打字速度：每分钟"+sudu .ToString ()+"字符";label1.Visible = true;}}private void timer1_Tick(object sender, EventArgs e){second++;}}简单的数据库连接：static void Main(string[] args){string connstr = "data Source=(local);initial catalog=student;userID=sa;password=sa";SqlConnection sqlconn = new SqlConnection(connstr);sqlconn.Open();string sql = "select stuid as 学号,stuname as 姓名,sex as 性别,classid as 班级号from studentInfo;";SqlCommand cmd = new SqlCommand(sql, sqlconn);SqlDataReader dr;dr = cmd.ExecuteReader();//读下一条记录while (dr.Read())//显示字段内容{Console.WriteLine("学号：" + dr["学号"].ToString() + "姓名：" + dr["姓名"].ToString() + "性别：" + dr["性别"].ToString() + "班级ID：" + dr["班级号"].ToString()); }Console.Read();}Get、Set访问器：（boss）class Boss{public Boss(){Console.WriteLine("我是老板，");}private string name;private string sex;private string company;public string Name{get { return name; }set { name = value; }}public string Sex{get { return sex; }set { sex = value; }}public string Company{get { return company; }set { company = value; }}public string Introduce(){return"姓名：" + Name + " ，性别：" + Sex + " ，公司名称：" + Company;}}如何获取当前系统时间DateTime d= System.Date.Now;int y=d.year;Timer事件何时触发tick()每隔2s，显示字幕。