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

转载于:https://www.cnblogs.com/zhengrunqiang/archive/2012/10/08/2715066.html