using System;
using System.Collections.Generic;
namespace ConsoleApp2
{class Program{static void Main(string[] args){//c#语言对表达式的定义：a sequence of one or more operands and zero or more operators can be evaluated to a single value object method namespace//consist os literal value a method invocation an operator and its operands and simple name//single value/*int x;x = 199;//object using System.Windows.Forms;List<int> intList = new List<int>() { 1, 2, 3 };double[]doubleArray = new double[] { 1.0, 2.0, 3.0 };var y = intList[1];Console.WriteLine(x.GetType());*///选择语句嵌套/* int score = 90;if (score >= 60)if (score >= 85)Console.WriteLine("best!");elseConsole.WriteLine("good");elseConsole.WriteLine("failed");*/// 声明语句：/* var y = 100;Console.WriteLine(y.GetType().FullName);int[] myArray = { 1, 2, 3 };Console.WriteLine(myArray[2]);const int x = 100;//常量声明必须跟初始化器*///语句分为：标签语句。声明语句，嵌入式语句//表达式语句//块语句 语句只能出现在方法体里，// 块语句是一条完整语句 ctrl +}快捷键在花括号之间跳转，作用域/*{hello: Console.WriteLine("hello world");goto hello;} *///选择语句bool 关系表达式是bool类型if 只有一条嵌入语句 代码提示，可以生成代码块//else语句 多用边界数据测试 else if/* int score = 60;if(score >=80 &&score <=100){Console.WriteLine("A");}else if (score>=60){Console.WriteLine("B");}else if (score>=40){Console.WriteLine("C");}else if (score>=0){Console.WriteLine("D");}*//* //switch语句 例子是：成绩判断Level myLevel = Level.High;//switch打出来先TAB，再条件里修改myLevel再回车switch (myLevel){case Level.High:break;case Level.Mid:break;case Level.Low:break;default:break;} *//* Calculator c = new Calculator();int r = c.Add("100","200");Console.WriteLine(r);*///do语句至少执行一次, while语句可能一次都不执行，如果while判断是false类型/* int score = 0;bool canContinue = true;do{Console.WriteLine("please input first number");string str1 = Console.ReadLine();int x = 0;try{x = int.Parse(str1);}catch {Console.WriteLine("First number has problem!restart");continue;}Console.WriteLine("please input second number");string str2 = Console.ReadLine();if (str2.ToLower()=="end"){break;}int y = 0;try{y = int.Parse(str2);}catch {Console.WriteLine("second number has problem,restart");continue;}int sum = x + y;if (sum == 100){score++;Console.WriteLine("Correct!{0}+{1} = {2} ", x, y, sum);}else{Console.WriteLine("Error!{0}+{1} = {2}", x, y, sum);canContinue = false;}} while (canContinue);Console.WriteLine("your score is {0}", score);Console.WriteLine("game over!"); *///for语句计数循环 tab修改/*for ( int counter = 0; counter < 10; counter++){Console.WriteLine("hello world");}//打印9*9乘法表for (int a = 1; a <=9; a++){for (int b = 0; b <=9; b++){Console.WriteLine("*");}}*/Calculator c = new Calculator();int result = c.Add("ABD", "12");Console.WriteLine(result);}/* enum Level{High,Mid,Low}*///try-catch 对异常值的处理class Calculator{public int Add(string arg1, string arg2){int a = 0;int b = 0;try{a = int.Parse(arg1);b = int.Parse(arg2);}//通用捕捉异常的语句catch(ArgumentNullException ane){Console.WriteLine(ane.Message);Console.WriteLine("your argument are null");}//捕捉特定异常的catch语句catch(FormatException fe){Console.WriteLine(fe.Message);Console.WriteLine("FORMAT WRONG");}catch(OverflowException oe){Console.WriteLine(oe.Message);Console.WriteLine("out of range!");}//释放系统资源 关闭数据库 程序的LOGfinally {}//变量作用阈不会超过声明她的语句块int result = a + b;return result;}}}}
