using System;

using System.Collections.Generic;

using System.Linq;

​

var array = new Hoge[]{

    new(18, "Alice"),

    new(19, "Bob"),

    new(20, "Charlie"),

    new(21, "Dave"),

};

​

var dic = array.ToDictionary(x => x.Age);

​

foreach (var (k, v) in dic)

{

    Console.WriteLine($"{k} => {v}");

}

​

record Hoge(int Age, string Name);