C#编程（1_初识表达式和变量）

 1 namespace ConsoleApplication1
 2 {
 3     class Program
 4     {
 5         static void Main(string[] args)
 6         {
 7             Console.WriteLine("The frist app in Beginning C# programming!");
 8             Console.ReadKey();
 9         }
10     }
11 }

 1 namespace WindowsFormsApplication1
 2 {
 3     public partial class Form1 : Form
 4     {
 5         public Form1()
 6         {
 7             InitializeComponent();
 8         }
 9 
10         private void button1_Click(object sender, EventArgs e)
11         {
12             MessageBox.Show("这是一个WinForm应用程序！");
13         }
14     }
15 }

 1 namespace ConsoleApplication1
 2 {
 3     class Program
 4     {
 5         static void Main(string[] args)
 6         {
 7             //声明两个变量，一个int类型变量，一个string类型变量
 8             int myInteger;
 9             string myString;
10 
11             //分别为已声明的变量赋初值
12             myInteger = 1989;
13             myString="myInteger is ";//如需换行，使用换行符“/n”
14 
15             Console.WriteLine("{0}{1}",myString,myInteger);//字符串实际上是插入变量内容的一个模板，字符串中的每对花括号都是一个占位符，包含列表中每个变量的内容
16             Console.ReadKey();
17         }
18     }
19 }

 1 namespace ConsoleApplication1
 2 {
 3     class Program
 4     {
 5         static void Main(string[] args)
 6         {
 7             //定义变量
 8             double firstNumber, secondNumber;
 9             string userName;
10 
11             //变量赋初值，分别读取用户输入的内容并存储到相应的变量中
12             Console.WriteLine("Enter you name:");
13             userName=Console.ReadLine();
14             Console.WriteLine("Welcome {0}!",userName);
15             Console.WriteLine("Give me a number:");
16             firstNumber=Convert.ToDouble(Console.ReadLine());
17             Console.WriteLine("Now Give me anther number:");
18             secondNumber=Convert.ToDouble(Console.ReadLine());
19             //输出（变量运算）
20             Console.WriteLine("{0}+{1}={2}", firstNumber, secondNumber, firstNumber + secondNumber);
21             Console.WriteLine("{0}-{1}={2}", firstNumber, secondNumber, firstNumber - secondNumber);
22             Console.WriteLine("{0}*{1}={2}", firstNumber, secondNumber, firstNumber * secondNumber);
23             Console.WriteLine("{0}/{1}={2}", firstNumber, secondNumber, firstNumber / secondNumber);
24             Console.ReadKey();
25         }
26     }
27 }