C# appending values to string[] doesn't work

Question

So I'm trying to append values to a list (in Json []), that's empty or has items in it. So I check wether the list in the object has items in it or not, if the item doesn't exist, then it creates a new item, if it exists, it rewrites it's value. Here is the code:

if (e.Key == Key.Enter)
{
    // When the user pressed enter, do action
    Team selected_team = teams.Where(t => t.team_number == Convert.ToInt32(inp_team_number.Text)).FirstOrDefault();

    if (selected_team != null)
    {
        // when the team number is given, go try and find the data of them
        Results team_results = results.Where(r => r.team_number == Convert.ToInt32(inp_team_number.Text)).FirstOrDefault();

        int index = (Convert.ToInt32(gtk_input.Name.Substring(gtk_input.Name.Length - 1)) - 1);

        // Check if the item in the list exists
        if (index < team_results.results[inp_tour_part.SelectedIndex].gtks.Length && team_results.results[inp_tour_part.SelectedIndex].gtks[index] != null)
        {
            if (regexColon.Match(gtk_input.Text).Success == true)
            {
                team_results.results[inp_tour_part.SelectedIndex].gtks[(Convert.ToInt32(gtk_input.Name.Substring(gtk_input.Name.Length - 1)) - 1)] = gtk_input.Text; // Give the new value
            }
            else
            {
                MessageBox.Show("Wrong value.", "An error occured", MessageBoxButton.OK, MessageBoxImage.Warning);
                team_results.results[inp_tour_part.SelectedIndex].gtks[(Convert.ToInt32(gtk_input.Name.Substring(gtk_input.Name.Length - 1)) - 1)] = "00:00"; // Give the default value
            }
        }
        else
        {
            if (regexColon.Match(gtk_input.Text).Success == true)
            {
                team_results.results[inp_tour_part.SelectedIndex].gtks.Append(gtk_input.Text); // Give the new value
            }
            else
            {
                MessageBox.Show("Wrong value.", "An error occured", MessageBoxButton.OK, MessageBoxImage.Warning);
                team_results.results[inp_tour_part.SelectedIndex].gtks.Append("00:00"); // Give the default value
            }
        }

        SaveResults(results);
        // Move to the next UI element
        MoveToNextUIElement(e);
    }
    else
    {
        MessageBox.Show("Something went somewhere wrong.", "An error occured", MessageBoxButton.OK, MessageBoxImage.Warning);
    }
}

Now, it works fine to rewrite the items, but when the list is empty (default) or when the item doesn't exist, and it needs to add/append the new value, it doesn't crahs and doesn't throw any error... Also it doesn't add the value to my json, now when I initialize the new object for this, it looks like the following:

team_results = new Results()
{
    team_number = selected_team.team_number,
    results = new Result[2] { new Result{ }, new Result { } } // Fixed length of array for the results. TODO: Needs fix.
};

And the model looks like this:

namespace RittensportRekenSoftware.Models
{
    public class Results
    {
        public int team_number { get; set; }
        public Result[] results { get; set; }
    }

    public class Result
    {
        public string given_start_time { get; set; }
        public string connection_to_start { get; set; }
        public string start_kp { get; set; }
        public string stop_kp { get; set; }
        public int missed_controls { get; set; }
        public float km { get; set; }
        public string[] gtks { get; set; }
    }
}

Now I just need a list of strings in my json, but I don't have any clue on how to achieve this...

You can't simply append to an array. That's why we have List. — Thomas Weller
– Thomas Weller, Commented Aug 1, 2018 at 18:09

Sach · Accepted Answer · 2018-08-01 18:15:56Z

2

If you MUST, you can resize an array using Array.Resize() method. Please see documentation here.

int[] array = new int[] { 1, 2, 3 };
Array.Resize(ref array, 5);
array[3] = 4;
array[4] = 5;

But it is strongly advised the use of List<T> instead of arrays. After all List<T> uses arrays behind the scenes so you get all the functionality of an array minus most of the cons.

answered Aug 1, 2018 at 18:15

Sach

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2 Comments

Robin Over a year ago

And how should I implement this into my current system?

Sach Over a year ago

Moral of the story is don't use this in your current system unless you really have to. Instead use a List<Result> for your results array.

Oleh Poshelugniy · Accepted Answer · 2018-08-01 18:40:57Z

0

You can use List instead. Thus you don't need to know the array size when instantiating the list.

answered Aug 1, 2018 at 18:40

Oleh Poshelugniy

213 bronze badges

6 Comments

Robin Over a year ago

I've used a list instead, but now when there is 1 value already in it, and I'm trying to add a new item, it crashes with ArgumentOutOfRange exception...

Oleh Poshelugniy Over a year ago

Ok I think you can implement a method which wouild create a new array based on original one. Then, you would be able to override that original array with the resulted one (returned by that new method).

Oleh Poshelugniy Over a year ago

The example code would be the following:

var test = new string[1] { "Test string 1" };              test = AddItemToArray(test, "Test string 2");     private static string[] AddItemToArray(string[] original, string item)         {             var result = new string[original.Length + 1];              for (int i = 0; i < original.Length; i++)             {                 result[i] = original[i];             }              result[result.Length - 1] = item;              return result;         }

Hans Keﬆing Over a year ago

@OlehPoshelugniy please edit that example into your answer. Code in comments is hard to read and extending your answer makes your answer better

d219 Over a year ago

Looks like you may have created a new answer instead of editing this one

|

ivcubr · Accepted Answer · 2018-08-01 19:48:07Z

Why not alter your models so they implement List instead of array. In the constructor of each model just initialize the empty list (or other action depending on your situation)

namespace RittensportRekenSoftware.Models
{
    public class Results
    {
        public int team_number { get; set; }
        public List<Result> results { get; set; }

        public Results() {
            results = new List<Result>();
        }
    }

    public class Result
    {
        public string given_start_time { get; set; }
        public string connection_to_start { get; set; }
        public string start_kp { get; set; }
        public string stop_kp { get; set; }
        public int missed_controls { get; set; }
        public float km { get; set; }
        public List<string> gtks { get; set; }

        public Result() {
            gtks = new List<string>();
        }
    }
}

Then when you have your models you can add to each list like the following:

Results r = new Results();
r.results.Add(new Result()); // or other `result` object here

Result r = new Result();
r.gtks.Add("My String"); // or other `string` here

Oleh Poshelugniy · Accepted Answer · 2018-08-02 11:28:16Z

0

I think you can implement a method which would create a new array based on original one. Then, you would be able to override that original array with the resulted one (returned by that new method).

The example code would be the following:

var test = new string[1] { "Test string 1" };

test = AddItemToArray(test, "Test string 2");


private static string[] AddItemToArray(string[] original, string item)
{
    var result = new string[original.Length + 1];

    for (int i = 0; i < original.Length; i++)
    {
        result[i] = original[i];
    }

    result[result.Length - 1] = item;

    return result;
}

edited Aug 2, 2018 at 11:28

answered Aug 2, 2018 at 8:30

Oleh Poshelugniy

213 bronze badges

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