C# 基本语法入门

C#读作 C Sharp是由 Microsoft 开发的面向对象编程语言广泛用于桌面应用、Web开发、游戏开发和企业级系统。1. 第一个 C# 程序using System; class Program { static void Main(string[] args) { Console.WriteLine(Hello World!); } }运行结果Hello World!2. 变量定义变量用于存储数据。int age 25; string name 张三; double salary 8000.50; bool isMale true; Console.WriteLine(name);常用数据类型类型说明示例int整数100double小数3.14decimal高精度小数99.99mchar单字符Astring字符串Hellobool布尔值true/falseDateTime日期时间DateTime.Now3. 常量const double PI 3.1415926;常量定义后不可修改。4. 运算符算术运算int a 10; int b 3; Console.WriteLine(a b); //13 Console.WriteLine(a - b); //7 Console.WriteLine(a * b); //30 Console.WriteLine(a / b); //3 Console.WriteLine(a % b); //1比较运算a b a b a b a ! b a b a b逻辑运算 //且 || //或 ! //非5. 输入输出输出Console.WriteLine(输出后换行); Console.Write(输出不换行);输入Console.Write(请输入姓名); string name Console.ReadLine(); Console.WriteLine(你好 name);6. 条件语句ifint score 85; if (score 60) { Console.WriteLine(及格); }if...elseif (score 60) { Console.WriteLine(及格); } else { Console.WriteLine(不及格); }switchint day 3; switch(day) { case 1: Console.WriteLine(星期一); break; case 2: Console.WriteLine(星期二); break; default: Console.WriteLine(其它); break; }7. 循环语句forfor(int i 1; i 5; i) { Console.WriteLine(i); }whileint i 1; while(i 5) { Console.WriteLine(i); i; }do...whileint i 1; do { Console.WriteLine(i); i; } while(i 5);foreachstring[] names {张三,李四,王五}; foreach(string item in names) { Console.WriteLine(item); }8. 数组int[] nums {1,2,3,4,5}; Console.WriteLine(nums[0]);遍历数组foreach(int num in nums) { Console.WriteLine(num); }9. 方法函数定义方法static int Add(int a,int b) { return a b; }调用方法int result Add(10,20); Console.WriteLine(result);10. 类和对象定义类class Student { public string Name; public int Age; public void ShowInfo() { Console.WriteLine($姓名{Name}); Console.WriteLine($年龄{Age}); } }创建对象Student stu new Student(); stu.Name 张三; stu.Age 18; stu.ShowInfo();11. 属性Property推荐使用属性而不是公开字段。class Student { public string Name { get; set; } public int Age { get; set; } }使用Student stu new Student(); stu.Name 李四; stu.Age 20;12. 异常处理try { int a 10; int b 0; Console.WriteLine(a / b); } catch(Exception ex) { Console.WriteLine(ex.Message); } finally { Console.WriteLine(程序结束); }13. 集合 Listusing System.Collections.Generic; Liststring names new Liststring(); names.Add(张三); names.Add(李四); names.Add(王五); foreach(string item in names) { Console.WriteLine(item); }14. 字符串插值string name 张三; int age 18; Console.WriteLine($姓名{name}年龄{age});15. 命名空间namespace MyProject { class Program { static void Main() { } } }