C#中泛型學習筆記

　　前言：這篇部落格我主要說一下C#中泛型的使用，也就是List和Dictionary字典集合的使用，我在這裡說的主要說的是如何去使用，而不是長篇大論的去研究泛型的底層，但我們有一定程式的時候在研究，使學習的能夠很快的學習集合然後自己研究集合的一些進階用法，不在最後還列舉出了一些常用的小案例。

1. 泛型集合

(1) 泛型集合就是不確定的集合，文法中有一個角括弧，裡面放什麼類型，這個集合就變成什麼類型

(2)List

            1)舉例說明：

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>)

            定義一個泛型集合：Dictionary<TKey,Tvalue> dic=new Dictionary<TKey,Tvalue>();

            1)增加

                   Add 將指定的索引值對添加到字典集合中

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

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("添加失敗，請檢查");}

                          //輸出結果是添加失敗，請檢查,以為添加了相同的鍵

            2)刪除

                   Remove 從字典集合中移除指定的鍵的值

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

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);}//輸出結果：bmp dib rtfClear 從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);         } //輸出結果為空白

            3)查詢

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

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

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("已經存在");}

                                 //輸出結果：已經存在

                   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("已經存在");

                                 }

                                 //輸出結果：已經存在

            4)TryGetValue 獲得於指定的鍵相關聯的值

                   方法原型:bool dic.TryGetValue(TKey key,out TVlaue 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");string value = "";if (openWith.TryGetValue("rtf", out value)){       Console.WriteLine("Key=rtf,value={0}", value);}else{         Console.WriteLine("根據rtf鍵沒有找到對應的值");}

                          //輸出結果：key=rtf,value=wordpad.exe

                   1)舉例說明：

                          static void Main(string[] args)

                          {

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

                                 dic.Add('1', "愛情這東西");

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

                                 {

                                        Console.WriteLine(item);

                                 }

                                 Console.ReadKey();

                          }

     (4)案例1：把分揀奇數的程式用泛型實現

 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>();//奇數            List<string> even = new List<string>(); //偶數            //3 for迴圈判斷奇偶            for (int i = 0; i < nums.Length; i++)            {                //第一種方法                //int num = Convert.ToInt32(nums[i]);                //if (num % 2 == 0)                //{                //    even.Add(nums[i]);                //}                //else                //{                //    odd.Add(nums[i]);                //}                //第二種方法                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轉換            Console.WriteLine(string.Join(" ", odd.ToArray()));        }

     (5)案例2：將int數組中的奇數放到一個新的int數組中返回

 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：從一個整數的List<int>中取出最大數

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轉換為"壹貳三"

 static void Main(string[] args)        {            string var = "壹貳三肆伍陸柒捌玖";            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("請輸入一行數字：");                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)計算字串中每種字元出現的次數

static void Main(string[] args)        {            Dictionary<char, int> dic = new Dictionary<char, int>();            Console.Write("請輸入一句話");            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))                {                    //如果集合不存在這個資料                    //dic[current] += 1;                    dic[current]++;                }                else                {                    //如果集合中不存在這個資料                    dic.Add(current, 1);                }            }            foreach (KeyValuePair<char, int> item in dic)            {                Console.WriteLine("子符{0}出現了{1}次", item.Key, item.Value);            }            Console.ReadKey();        }

1. Dictionary就是Hashtable的泛型形式

(1) 哈爾演算法是一個函數

            Add(Key,Value);

            dic[Key];

(2)雜湊演算法是一個通過Key來計算地址的函數

            1)傳入一個key和一個value後

            2)通過雜湊演算法計算key的到一個地址

            3)將地址存入索引值對集合，並將value存入地址所在的地方

            4)等到訪問的時候直接通過key計算出地址，直接找到儲存的變數

1. 能不能用for迴圈遍曆一個集合Dic

(1) 在for迴圈中如果不使用對應的遞增序號，"我"就認為不叫使用了for迴圈

     (2)foreach迴圈的過程

            1)找到資料來源，調用GetEnumertor方法，得到枚舉值

            2)in,調用MoveNext方法

            3)如果MoveNext返回true,使用Current得到當前資料

            4)如果返回false,則跳出迴圈

                   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. 等於

(1) Equals 確定指定的Object是否等於當前的Object類型

            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));

                   輸出結果： False,True