**
2.1 编写控制台程序，定义两个单精度实数x、y,值分别为78.5和85.5，求两个数之和**
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace TEXT1
{
class Program
{
static void Main(string[] args)
{
float X = 78.5f;
float Y = 85.5f;
float z;
z = X + Y;
Console.WriteLine(z);
Console.ReadKey();
}
}
}
**
2.2编写控制台程序，定义两个整数（两个整数的值从键盘输入），定义一个字符串变量，当这个字符变量分别是“+”、“-”、“*”、“/”时，用switch语句输出这两个数的运算结果。（提示：用到的方法有ReadLine()int.Parse()Convert.ToInt32()等）**
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace TEXT2
{
class Program
{
static void Main(string[] args)
{
int num1, num2;
string ch;
Console.WriteLine("请从键盘上输入两个整数：");
num1 = int.Parse(Console.ReadLine());//从键盘上输入1行字符
num2 = Convert.ToInt32(Console.ReadLine());
Console.WriteLine("请从键盘上输入运算符号：");
ch = Console.ReadLine();
switch(ch){
case "+": Console.WriteLine(num1 + num2); break;
case "-": Console.WriteLine(num1 - num2); break;
case "*": Console.WriteLine(num1 * num2); break;
case "/": Console.WriteLine(num1 / num2); break;
}
Console.ReadKey();
}
}
}
**
完成从键盘接受一个成绩，按照优秀（90-100）、良好（70-89）、及格（60-69）、不及格输出等级等级。**
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace TEXT3
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("请输入一个分数：");
float x = int.Parse(Console.ReadLine());;
if (x >= 90)
{
Console.WriteLine("优秀");
Console.ReadKey();
}
else if (x >= 80)
{
Console.WriteLine("良好");
Console.ReadKey();
}
else if (x >= 70)
{
Console.WriteLine("中等");
Console.ReadKey();
}
else if (x >= 60)
{
Console.WriteLine("及格");
Console.ReadKey();
}
else
{
Console.WriteLine("不及格");
Console.ReadKey();
}
}
}
}
**
打印九九乘法表**
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace TEXT4
{
class Program
{
static void Main(string[] args)
{
for (int i = 1; i < 10; i++)
{
for (int s = 1; s <= i; s++)
{
Console.Write(s + "*" + i + "=" + i * s + " ");
if (i == s)
{
Console.Write("n");
}
}
}
Console.Write("请按任意键退出");
Console.ReadKey();
}
}
}
**
猜是否是闰年**
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace TEXT5
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
int year;
year = int.Parse(textBox1.Text);
if(year%4==0 &&year/100!=0||year%400==0)
{
textBox2.Text=string.Format("{0}年是闰年！",year);
}else{
textBox2.Text=string.Format("{0}年不是闰年！",year);
}
}
private void textBox2_TextChanged(object sender, EventArgs e)
{
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
}
}
}
