90 lines
3.0 KiB
C#
90 lines
3.0 KiB
C#
using System.Collections.Generic;
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namespace Lesson8_Dictionary
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{
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internal class Program
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{
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static void Main(string[] args)
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{
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#region 知识点一 Dictionary本质
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//可以将Dictionary理解为 拥有泛型的Hashtable
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//他也是极于剑的哈希代码组织起来的 键/值对
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//键值对类型从Hashtable的object变为了可以自己指定的泛型
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#endregion
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#region 知识点二 声明
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Dictionary<int, string> dictionary = new Dictionary<int, string>();
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#endregion
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#region 知识点三 增删查改
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#region 增
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//注意：不能出现相同键
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dictionary.Add(1, "111");
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dictionary.Add(2, "222");
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dictionary.Add(3, "333");
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#endregion
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#region 删
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//1.只能通过键去删除
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// 删除不存在的键 无反应
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dictionary.Remove(1);
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dictionary.Remove(4);
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//2.清空
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dictionary.Clear();
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#endregion
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#region 查
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//1.通过键查看值
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//注意：找不到直接报错，而不是像hashtable一样无反应
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dictionary.Add(1, "111");
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dictionary.Add(2, "222");
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dictionary.Add(3, "333");
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Console.WriteLine(dictionary[2]);//"222"
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//Console.WriteLine(dictionary[4]);//不会像hashtable一样无反应而是直接报错
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//2.查看是否存在
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// 根据键检测
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if (dictionary.ContainsKey(1) )
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{
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Console.WriteLine("存在键为1的键值对");
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}
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// 根据值检测
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if (dictionary.ContainsValue("111"))
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{
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Console.WriteLine("存在值为111的键值对");
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}
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#endregion
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#region 改
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Console.WriteLine(dictionary[1]);
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dictionary[1] = "999";
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Console.WriteLine(dictionary[1]);
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#endregion
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#endregion
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#region 知识点四 遍历啊
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Console.WriteLine("---------------------------");
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//长度
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Console.WriteLine(dictionary.Count);
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//1.遍历所有键
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Console.WriteLine("---------------------------");
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foreach (int item in dictionary.Keys)
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{
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Console.WriteLine(item);
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Console.WriteLine(dictionary[item]);
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}
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//2.遍历所有值
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Console.WriteLine("---------------------------");
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foreach (string item in dictionary.Values)
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{
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Console.WriteLine(item);
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}
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//3.键值对一起遍历
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Console.WriteLine("---------------------------");
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foreach (KeyValuePair<int, string> pair in dictionary)
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{
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Console.WriteLine($"键：{pair.Key} 值:{pair.Value}");
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}
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#endregion
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}
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}
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}
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