Dictionary 可以不經過大小寫轉換就可以查詢摟！

只需要加上StringComparer.OrdinalIgnoreCase

using System;
using System.Collections.Generic;

namespace Test
{
    class Program
    {
        static void Main(string[] args)
        {
            Dictionary<string, string> d = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
            {
                { "AbCdEfG" , "123456" }
            };
            Console.WriteLine(d["abcdefg"]);
        }
    }
}