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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。

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：

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)

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);

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);

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);

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

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

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

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"

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

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();
 
        }

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

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);

}

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

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原文地址：https://www.cnblogs.com/zhengrunqiang/p/2715066.html