C#中泛型学习笔记

　　前言：这篇博客我主要说一下C#中泛型的使用，也就是List和Dictionary字典集合的使用，我在这里说的主要说的是如何去使用，而不是长篇大论的去研究泛型的底层，但我们有一定程序的时候在研究，使学习的能够很快的学习集合然后自己研究集合的一些高级用法，不在最后还列举出了一些常用的小案例。

1. 泛型集合

(1) 泛型集合就是不确定的集合，语法中有一个尖括号，里面放什么类型，这个集合就变成什么类型

(2)List

            1)举例说明：

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static void Main(string[] args)   {           List<int> listInt = new List<int>();           listInt.AddRange(new int[] { 1, 34, 54, 65, 76, 78 });           int sum = 0;           for (int i = 0; i < listInt.Count; i++)             {                    sum += listInt[i];            }            Console.WriteLine(sum);            Console.ReadKey();   }

     (3)Dictionary  (Dictionary<TKey,TValue>)

            定义一个泛型集合：Dictionary<TKey,Tvalue> dic=new Dictionary<TKey,Tvalue>();

            1)增加

                   Add 将指定的键值对添加到字典集合中

                   方法原型：void dic.Add(T key,T Value)

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Dictionary<string, string> openWith =new Dictionary<string, string>();    try   {             openWith.Add("txt", "notepad.exe");             openWith.Add("bmp", "paint.exe");             openWith.Add("dib", "paint.exe");             openWith.Add("rtf", "wordpad.exe");             openWith.Add("txt", "winword.exe");   }   catch (ArgumentException)   {              Console.WriteLine("添加失败，请检查");   }

                          //输出结果是添加失败，请检查,以为添加了相同的键

            2)删除

                   Remove 从字典集合中移除指定的键的值

                          方法原型：bool dic.Remove(TKey key);                     

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Dictionary<string, string> openWith =new Dictionary<string, string>();   openWith.Add("txt", "notepad.exe");   openWith.Add("bmp", "paint.exe");   openWith.Add("dib", "paint.exe");   openWith.Add("rtf", "wordpad.exe");   openWith.Remove("txt");    foreach (var item in openWith)   {          Console.WriteLine(item.Key);   }   //输出结果：bmp dib rtf   Clear 从字典集合中移除所有的值    方法原型: void dic.Clear();            Dictionary<string, string> openWith =new Dictionary<string, string>();            openWith.Add("txt", "notepad.exe");            openWith.Add("bmp", "paint.exe");            openWith.Add("dib", "paint.exe");            openWith.Add("rtf", "wordpad.exe");            openWith.Clear();            foreach (var item in openWith)            {                   Console.WriteLine(item.Key);            }    //输出结果为空

            3)查询

                   ContainsKey 得到字典集合中是否包含指定的键

                          方法原型：bool dic.ContainsKey(TKey,key);     

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Dictionary<string, string> openWith = new Dictionary<string, string>();   openWith.Add("txt", "notepad.exe");   openWith.Add("bmp", "paint.exe");   openWith.Add("dib", "paint.exe");   openWith.Add("rtf", "wordpad.exe");   if (!openWith.ContainsKey("txt"))   {             openWith.Add("txt", "notepat++");   }   else   {            Console.WriteLine("已经存在");   }

                                 //输出结果：已经存在

                   COntainsValue 得到字典集合中是否包含指定的值

                          方法原型：bool dic.ContainsValue(TValue,value);

                                 Dictionary<string, string> openWith = new Dictionary<string, string>();

                                 openWith.Add("txt", "notepad.exe");

                                 openWith.Add("bmp", "paint.exe");

                                 openWith.Add("dib", "paint.exe");

                                 openWith.Add("rtf", "wordpad.exe");

                                 if (openWith.ContainsValue("paint.exe"))

                                 {

                                        Console.WriteLine("已经存在");

                                 }

                                 //输出结果：已经存在

            4)TryGetValue 获得于指定的键相关联的值

                   方法原型:bool dic.TryGetValue(TKey key,out TVlaue value);

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Dictionary<string, string> openWith = new Dictionary<string, string>();   openWith.Add("txt", "notepad.exe");   openWith.Add("bmp", "paint.exe");   openWith.Add("dib", "paint.exe");   openWith.Add("rtf", "wordpad.exe");   string value = "";   if (openWith.TryGetValue("rtf", out value))   {          Console.WriteLine("Key=rtf,value={0}", value);   }   else   {            Console.WriteLine("根据rtf键没有找到对应的值");   }

                          //输出结果：key=rtf,value=wordpad.exe

                   1)举例说明：

                          static void Main(string[] args)

                          {

                                 Dictionary<char, string> dic = new Dictionary<char, string>();

                                 dic.Add('1', "爱情这东西");

                                 foreach (KeyValuePair<char, string> item in dic)

                                 {

                                        Console.WriteLine(item);

                                 }

                                 Console.ReadKey();

                          }

     (4)案例1：把分拣奇数的程序用泛型实现

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static void Main(string[] args)          {              string str = "3 45 65 34 68 67 87 98";              //1 split              string[] nums = str.Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);              //2 list<string>              List<string> odd = new List<string>();//奇数              List<string> even = new List<string>(); //偶数              //3 for循环判断奇偶              for (int i = 0; i < nums.Length; i++)              {                  //第一种方法                  //int num = Convert.ToInt32(nums[i]);                  //if (num % 2 == 0)                  //{                  //    even.Add(nums[i]);                  //}                  //else                  //{                  //    odd.Add(nums[i]);                  //}                  //第二种方法                  string num = nums[i];                  char ch = num[num.Length - 1];                  int last = ch - '0';                  if ((nums[i][nums[i].Length - 1] - '0') % 2 == 0)                  {                      even.Add(nums[i]);                  }                  else                  {                      odd.Add(nums[i]);                  }              }              odd.AddRange(even);              //4转换              Console.WriteLine(string.Join(" ", odd.ToArray()));          }

     (5)案例2：将int数组中的奇数放到一个新的int数组中返回

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static void Main(string[] args)          {              int[] nums = { 1, 3, 5, 565, 76, 78, 98, 90, 4, 545 };              List<int> listInt = new List<int>();              for (int i = 0; i < nums.Length; i++)              {                  if (nums[i] % 2 == 1)                  {                      listInt.Add(nums[i]);                  }              }              for (int i = 0; i < listInt.Count; i++)              {                  Console.WriteLine(listInt[i] + " ");              }              Console.ReadKey();          }

     (6)案例3：从一个整数的List<int>中取出最大数

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static void Main(string[] args)           {               int[] nums = { 2, 34, 454, 65, 76, 77, 778, 898, 989 };               int max = int.MinValue;               int min = int.MaxValue;               List<int> listInt = new List<int>();               listInt.AddRange(nums);               for (int i = 0; i < listInt.Count; i++)               {                   if (min > listInt[i])                   {                       min = listInt[i];                   }                   if (max < listInt[i])                   {                       max = listInt[i];                   }               }               Console.WriteLine(max);               Console.WriteLine(min);           }

     (7)把123转换为"壹贰叁"

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static void Main(string[] args)          {              string var = "壹贰叁肆伍陆柒捌玖";              Dictionary<char, char> dic = new Dictionary<char, char>();              for (int i = 0; i <var.Length ; i++)              {                  dic.Add((char)(i + '0'), var[i]);              }              while (true)              {                  Console.Write("请输入一行数字：");                  string str = Console.ReadLine();                  StringBuilder sb = new StringBuilder();                  for (int i = 0; i < str.Length; i++)                  {                      char num = str[i];                      char word = dic[num];                      sb.Append(word);                  }                  Console.WriteLine(sb.ToString());                  Console.ReadKey();              }          }

     (8)计算字符串中每种字符出现的次数

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static void Main(string[] args)           {               Dictionary<char, int> dic = new Dictionary<char, int>();               Console.Write("请输入一句话");               string str = Console.ReadLine();               for (int i = 0; i < str.Length; i++)               {                   //dic.Add(str[i], 1);                   //dic[str[i]]++;                   char current = str[i];                   if (dic.ContainsKey(current))                   {                       //如果集合不存在这个数据                       //dic[current] += 1;                       dic[current]++;                   }                   else                   {                       //如果集合中不存在这个数据                       dic.Add(current, 1);                   }               }               foreach (KeyValuePair<char, int> item in dic)               {                   Console.WriteLine("子符{0}出现了{1}次", item.Key, item.Value);               }               Console.ReadKey();           }

1. Dictionary就是Hashtable的泛型形式

(1) 哈尔算法是一个函数

            Add(Key,Value);

            dic[Key];

(2)哈希算法是一个通过Key来计算地址的函数

            1)传入一个key和一个value后

            2)通过哈希算法计算key的到一个地址

            3)将地址存入键值对集合，并将value存入地址所在的地方

            4)等到访问的时候直接通过key计算出地址，直接找到存储的变量

1. 能不能用for循环遍历一个集合Dic

(1) 在for循环中如果不使用对应的递增序号，"我"就认为不叫使用了for循环

     (2)foreach循环的过程

            1)找到数据源，调用GetEnumertor方法，得到枚举值

            2)in,调用MoveNext方法

            3)如果MoveNext返回true,使用Current得到当前数据

            4)如果返回false,则跳出循环

                   static void Main(string[] args)

                   {

                          Dictionary<string, string> dic = new Dictionary<string, string>();

                          dic.Add("1111", "2222");

                          dic.Add("0000", "3333");

                          var enumrator = dic.GetEnumerator();

                          //while (enumrator.MoveNext())

                          //{

                          //    Console.WriteLine(enumrator.Current.Key + "," + enumrator.Current.Value);

                          //}

                          for (; enumrator.MoveNext(); )

                          {

                                 Console.WriteLine(enumrator.Current.Key + "," + enumrator.Current.Value);

                          }

                   }

1. 等于

(1) Equals 确定指定的Object是否等于当前的Object类型

            方法原型：

                   bool Equals(Object obj)

                   Object Obj1 = new Object();

            Object Obj2 = new Object();

            Console.WriteLine(Obj1.Equals(Obj2));

            Obj2 = Obj1;

            Console.WriteLine(Obj1.Equals(Obj2));

                   输出结果： False,True