C# 中的多维关联 Arrays

Question

Started getting into C# from JS and PHP. I am getting used to the strict use of data types and I am struggling to figure out how to declare multidimensional associative array of different data types.

Like for example in PHP one would probably do something like this

 $roomDiscount["apartment"][0]["minDaysOfStay"] = 10;
 $roomDiscount["apartment"][0]["discount"] = 0.3;

 $roomDiscount["apartment"][1]["minDaysOfStay"] = 15;
 $roomDiscount["apartment"][1]["discount"] = 0.35;

 $roomDiscount["apartment"][2]["minDaysOfStay"] = 16;
 $roomDiscount["apartment"][2]["discount"] = 0.5;

 $roomDiscount["presidential suite"][0]["minDaysOfStay"] = 10;
 $roomDiscount["presidential suite"][0]["discount"] = 0.1;

 $roomDiscount["presidential suite"][1]["minDaysOfStay"] = 15;
 $roomDiscount["presidential suite"][1]["discount"] = 0.15;

 $roomDiscount["presidential suite"][2]["minDaysOfStay"] = 16;
 $roomDiscount["presidential suite"][2]["discount"] = 0.2;

So far I have been struggling with Dictionaries

private static void SkiTripWithDictionariesArrays()
        {
            int daysOfStay = int.Parse(Console.ReadLine());
            string typeOfAccomodation = Console.ReadLine().ToLower().Trim();
            string review = Console.ReadLine().ToLower().Trim();

            Dictionary<string, double> roomPrices = new Dictionary<string, double>();
            Dictionary<string, object> roomDiscounts = new Dictionary<string, object>(); // <---- thats the bugger
            Dictionary<string, double> reviewAdjustment = new Dictionary<string, double>();

           
            //populate room prices
            roomPrices.Add("room for one person", 18);
            roomPrices.Add("apartment", 25);
            roomPrices.Add("president apartment", 35);

        }

Answer 1

Your current PHP code is like this:

$roomDiscount["apartment"][0]["minDaysOfStay"] = 10;

It is close to this kind of structure in C#:

Dictionary<string, List<Dictionary<string, double>>>

Declaring such an object probably isn't a good way of going about it. Instead you should define class objects instead. The example I give below is for illustrative purposes only, and isn't necessarily the best way to do this (there are many different approaches to this situation):

public class RoomDiscount
{
    public int MinDaysOfStay {get;set;}
    public double Discount {get;set;}
}

public class RoomDiscounts
{
    public List<RoomDiscount> DiscountBands {get;set;}
}

Usage:

Dictionary<string, RoomDiscounts> discountDetails = new Dictionary<string, RoomDiscounts>();
discountDetails["apartment"] = new RoomDiscounts {
    DiscountBands = new List<RoomDiscount> {
        new RoomDiscount {
            MinDaysOfStay = 10,
            Discount = 0.3
        },            
        new RoomDiscount {
            MinDaysOfStay = 15,
            Discount = 0.35
        },            
        new RoomDiscount {
            MinDaysOfStay = 16,
            Discount = 0.5
        }
    }
};

string room = "apartment";
int daysOfStay = 26;
double discount = discountDetails[room].DiscountBands.OrderByDescending(b => b.MinDaysOfStay).FirstOrDefault(b => daysOfStay >= b.MinDaysOfStay)?.Discount ?? 0;

Again, this is just an example of one way you could organise your data in a more strongly-typed fashion. Note that this will throw an exception if the room type isn't defined, so you could use TryGetValue to retrieve the details from the dictionary.