Jagged arrays in C#

Question

Im trying to store to array of ints in a jagged array:

while (dr5.Read()) { customer_id[i] = int.Parse(dr5["customer_id"].ToString()); i++; }

dr5 is a datareader. I am storing the customer_id in an array, i also want to store scores in another array. I want to have something like below within the while loop

int[] customer_id = { 1, 2 }; int[] score = { 3, 4}; int[][] final_array = { customer_id, score };

Can anyone help me please ? EDIT: this is what i have tried. No values are being displayed.

 customer_id = new int[count]; score = new int[count]; int i = 0; while (dr5.Read()) { customer_id[i] = int.Parse(dr5["customer_id"].ToString()); score[i] = 32; i++; } int[][] final = { customer_id, score }; return this.final;

I don't think I've ever seen this deliberate an attempt to write C code in C# ;) — hemp
– hemp, Commented Jun 4, 2010 at 18:32

Mark Seemann · Accepted Answer · 2010-05-31 09:17:37Z

A better, more object-oriented approach would be to create a Customer class with a Scores property:

public class Customer { public Customer() { this.Scores = new List<int>(); } public IList<int> Scores { get; private set; } }

Since it turns out that there is only one score per customer, a more correct Customer class might look like this:

public class Customer { public int Score { get; set; } }

You might consider making the Score property read-only if you don't need to be able to update it afterwards.

I don't think each customer has a list of scores - given the second snippet, I think there's one score per customer.

Blindy · Accepted Answer · 2010-05-31 08:41:19Z

Do you know the size to start with? If so, you could do:

int[] customerIds = new int[size]; int[] scores = new int[size]; int index = 0; while (dr5.Read()) { customerIds[index] = ...; scores[index] = ...; index++; } int[][] combined = { customerIds, scores };

However, I would advise you to rethink. It sounds like you really want to associate a customer ID with a score... so create a class to do so. Then you can do:

List<Customer> customers = new List<Customer>(); while (dr5.Read()) { int customerId = ...; int score = ...; Customer customer = new Customer(customerId, score); customers.Add(customer); }

Amsakanna · Accepted Answer · 2010-05-31 08:44:52Z

As an alternative idea of using arrays:

If it is a one to one mapping you can use Dictionary for temporary storage like this:

var scores = new Dictionary<int, int>(); while (dr5.Read()) { scores.Add(int.Parse(dr5["customer_id"].ToString()), int.Parse(dr5["score"].ToString())); }

Else you can create a class customer and make a list out of it.

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