C#学习-索引器与Dictionary

sfdely

于 2024-12-22 23:35:43 发布

阅读量220

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CC 4.0 BY-SA版权

文章标签： c# 学习 android

本文链接：https://blog.youkuaiyun.com/sfdely/article/details/144654910

代码如下

namespace _03_索引器与Dictionary
{
    internal class Program
    {
        static void Main(string[] args)
        {
            Student stu = new Student();
            var mathScore = stu["Math"];    //不存在Math 故打印不出来
            Console.WriteLine(mathScore);
            stu["English"] = 99;
            var EnglishScore = stu["English"];
            Console.WriteLine(EnglishScore);
        }
    }

    class Student
    {
        private Dictionary<string, int> scoreDictionary = new Dictionary<string, int>();

        public int? this[string  subject]   //ind + 双击Tab键，快速插入 ?表示可控的int类型
        {
            get {
                if (this.scoreDictionary.ContainsKey(subject))
                {
                    return this.scoreDictionary[subject];
                }
                else
                    return null;
            }
            set { 
                if (value.HasValue == false)
                {
                    throw new Exception("Score cannot be null");
                }
                if (this.scoreDictionary.ContainsKey(subject))
                {
                    this.scoreDictionary[subject] = value.Value;
                }
                else
                {
                    this.scoreDictionary.Add(subject, value.Value);
                }
            }
        }
    }
}