断言

找到满足的子串定位位置左边和右边。左边断言（？<=条件）字符串必须满足左边某个条件的正则（？<!条件）； //右边断言（？=条件）（？!条件）帮我们定位

 //左边断言 （？<=条件）字符串必须满足左边某个条件的正则  （？<!条件）
 string str = "abc1234def123";
 string pattern = @"(?<!c)\d+";//括号中不参与匹配，只定位
 MatchCollection matches = Regex.Matches(str, pattern);
 foreach (Match i in matches)
 {
     Console.WriteLine(i);//234  123
 }
 
  //右边断言 （？=条件） （？!条件） 帮我们定位
  string str = "abc1234def1234";
  string pattern = @"(?<=3).+(?=1)";//在1前面，3的后面
  MatchCollection matches = Regex.Matches(str, pattern);
  foreach (Match i in matches)
  {
      Console.WriteLine(i);//4def
  }
  
  //把当前文件目录下的文件
  string pattern1 = @"(?<=\./).+( ?=\.txt)";
  string[] files = Directory.GetFiles("./");
  //MatchCollection matches = Regex.Matches(str, pattern1);
  foreach (string i in files)
  {
      Match match = Regex.Match(i, pattern1);
      if (match.Success) //match.Success匹配成功的时候就打印
          Console.WriteLine(match);//1.txt  2.txt
  }
  
  //使用（）匹配我们要的子串  字符串格式化  $"变量名占位"
  string pattern1 = @"(\./)(.+)\.txt$";
  string[] files = Directory.GetFiles("./");
  foreach (string i in files)
  {
      Match match = Regex.Match(i, pattern1);
      //Console.WriteLine(match.Groups[0]);//下标0为匹配到的子串
      //我想拿到括号中的字符
      Console.WriteLine(match.Groups[1]);//下标1为第一个括号匹配到的内容 //  ./   
      Console.WriteLine(match.Groups[2]);//下标2为第二个括号匹配到的内容 //  1
  }
  
  //第三种方式获取中间子串（？<占位符>正则*？）
  string pattern1 = @"\./(?<fileName>.+).txt$";//匹配左边是./ 右边是.txt且以.txt结尾
  string[] files = Directory.GetFiles("./");
  foreach (string i in files)
  {
      Match match = Regex.Match(i, pattern1);
      Console.WriteLine(match.Groups["fileName"]);//1   2
  }

Json

using LitJson;//一定要引入命名空间
public class Human {
            public Person person;
        }

public class Hometown
{
            public string provinxe;
            public string city;
            public string county;
            public override string ToString()
            {
                return $"provinxe:{provinxe},city:{city},county:{county}";
            }
 }
 public class Person
 {
            public string name;//空字符串
            public int age;
            public string sex;
            public Hometown hometown;
            public override string ToString()//打印对象可以直接看到里面的键值对
            {
                return $"name:{name},age:{age},sex:{sex},Hometown:{hometown} ";
            }
}
public class Sthdent
{
    public string name;//空字符串
    public string id;//0
    public override string ToString()//打印对象可以直接看到里面的键值对
    {
        return $"name:{name},id:{id}";
    }
}
  Sthdent stu = new Sthdent();
  Console.WriteLine(stu);//name:,id:
  
  Sthdent[] student = JsonMapper.ToObject<Sthdent[]>(File.ReadAllText("./json.txt"));
  foreach (Sthdent i in student)
  {
      Console.WriteLine(i.name);//小明 小强
  }
  
  //如果json的根是对象，用对象的形式拿数据
  Human student = JsonMapper.ToObject<Human>(File.ReadAllText("./jsons.txt"));
  Console.WriteLine(student.person);//name:王安石,age:200,sex:男,Hometown:provinxe:,city:九江市,county:清华三号
  
  //转字符串
   public class Animal2
    {
        public string name;
        public int age;
    }
    public class Animal
    {
        public Animal(string name,int age)
        {
            this.name = name;
            this.age = age;
        }
        public string name;
        public int age;
    }
     //对象转字符串
     Animal animal = new Animal("小黑", 18);//中文转成unicode
     string json = JsonMapper.ToJson(animal);
     Console.WriteLine(json);//{"name":"\u5C0F\u9ED1","age":18}
    
    int[] intArray = new int[] { 1, 2, 3, 4 };
    string json = JsonMapper.ToJson(intArray);//替换1.txt的内容为intArray的内容
    File.WriteAllText("./1.txt", json);
    //1.txt的内容为[1,2,3,4]
    
     Animal2 cate = JsonMapper.ToObject<Animal2>(File.ReadAllText("./1.txt"));
     Console.WriteLine(cate.name);//小黑

集合类

 //栈 注意：要引入命名空间 using System.Collections;
 //创建一个栈
 Stack stack = new Stack();
 //入栈
 stack.Push(1);//入栈的数据类型可以不同
 stack.Push("ddd");
 stack.Push(new Person());
 //查看栈中的值 只能读到栈顶的值
 object i = stack.Peek;//object可代表里面所有的类型
 Console.WriteLine(i);//
 
 int length = stack.Count;
 for (int j = 0; j < length; j++)//如何获取栈的长度 stack.Count
 {
     object i = stack.Peek();
     Console.WriteLine(i);//集合类.Person ddd  1
     stack.Pop();
 }
 
 
 //第二种
 while (stack.Count > 0)
 {
     object i = stack.Peek();
     Console.WriteLine(i);//集合类.Person ddd  1
     stack.Pop();
 }
 Console.WriteLine(stack.Contains("ddd"));//检查栈中是否包含某个元素，返回一个布尔值
 //练习：输入一个十进制数，转成二进制取余数入栈
  static void getBin(int num)
  {
      Stack stack = new Stack();
      while (num > 0)
      {
          int remainer = num % 2;
          //入栈
          stack.Push(remainer);
          num /= 2;
      }
      //出栈
      while (stack.Count > 0)
      {
          Console.Write(stack.Peek());
          stack.Pop();
      }

  }
  Console.WriteLine("请输入一个十进制数");
  int num = int.Parse(Console.ReadLine());
  getBin(num);
 
 //队列
Queue queue = new Queue();
//入队列
queue.Enqueue("ASD");
queue.Enqueue(213);
queue.Enqueue("name");
//出队列
//queue.Dequeue();//ASD已出
//拿到队列头的值
Console.WriteLine(queue.Peek());//213
Console.WriteLine(queue.Count);//2

//遍历
while (queue.Count > 0)
 {
     Console.WriteLine(queue.Peek());
     queue.Dequeue();
 }
Console.WriteLine(queue.Contains(213));
queue.Clear();//清空
Console.WriteLine(queue);
//练习
Random ran = new Random();
List<string> list = new List<string>() {"喜迎二十大","俄乌冲突","抗癌药", "喜迎十九大" , "喜迎十八大" };
Queue queue = new Queue();
while (queue.Count < 10)
{
    string str = list[ran.Next(0,list.Count)];
    queue.Enqueue(str);
}
while (queue.Count>0)
{          
    Console.WriteLine(queue.Peek());
    queue.Dequeue();
    Thread.Sleep(1000);
}

c#第十六课

断言

Json

集合类