Add textbox value to array and show this in listbox. Refresh the array when button clicked

Question

So I run into the following problem. I have a textbox and listbox. Ive made a array like this:

string[] Brands = new string[10];
            Brands[0] = "Yamaha";
            Brands[1] = "Suzuki";
            Brands[2] = "Harley";
            Brands[3] = "Kawasaki";

The array has place for 10 values, but I have specified only four values. I want to add up to ten values into this array with a click on the button.

I can not use a list, it has to be an array. I already discovered that I need to place the above part in the

{
    public partial class Form1 : Form        
    {

        string[] Brands = new string[10];
        Brands[0] = "Yamaha";
        Brands[1] = "Suzuki";
        Brands[2] = "Harley";
        Brands[3] = "Kawasaki";

But it doens't recognize the Brands[].

The

private void buttonAddbrand_Click(object sender, EventArgs e)
{

Needs to contain the code for adding it into the array. Like refreshing the array.

I'm stuck, too much information on the internet and everybody suggests a list, but I need to use an array. Help would be much appreciated.

Answer 1

to the answare of Ian sure you can initialize this in this way why not?

string[] Brands = new string[10];
Brands[0] = "Yamaha"; 
Brands[1] = "Suzuki"; 
Brands[2] = "Harley"; 
Brands[3] = "Kawasaki"; 

but also in this way

string[] Brands = new string[10] { "Yamaha", "Suzuki", "Harley", "Kawasaki" };

coming back to you problem why not creating your own class which do'S whatever you like it to

public class Brands 
{
    #region private 

    private int _maxCapacity { get; set; }
    private readonly List<string> _brands = new List<string>();

    #endregion

    #region Constructor 

    public Brands(int maxCapacity)
    {
        _maxCapacity = maxCapacity;
    }

    #endregion

    #region public 

    // return all as array
    public string[] AsArray
    {
        get { return _brands.ToArray(); }
    }

    /// <summary>
    /// recive the actual count
    /// </summary>
    public int Count
    {
        get { return _brands.Count; }
    }

    /// <summary>
    /// give item from position
    /// </summary>
    /// <param name="item"></param>
    /// <returns></returns>
    public string Get(int item)
    {
        return _brands.Count <= item ? _brands[item] : string.Empty;
    }

    /// <summary>
    /// Set(Add) a value if enougth capacity
    /// </summary>
    /// <param name="value"></param>
    public void Set(string value)
    {
        if (_brands.Count < _maxCapacity)
            _brands.Add(value);
        else
        {
            throw new ArgumentOutOfRangeException("Capacity");
        }
    }

    /// <summary>
    /// change an item
    /// </summary>
    /// <param name="item"></param>
    /// <param name="value"></param>
    public void Set(int item, string value)
    {
        if (_brands.Count <= item)
            _brands[item] = value;
    }

    #endregion
}

// i did not compile it but this is the idea so in your form you simply use it i hope that helps

best regards

Answer 2

You cannot assign the array like this:

public partial class Form1 : Form        
{

    string[] Brands = new string[10];
    Brands[0] = "Yamaha"; //fail
    Brands[1] = "Suzuki"; //fail
    Brands[2] = "Harley"; //fail
    Brands[3] = "Kawasaki"; //fail

In the class context. Instead, you should do something like this

public partial class Form1 : Form        
{

    string[] Brands = new string[10] { "Yamaha", "Suzuki", "Harley", "Kawasaki", "", "", "", "", "", "" };

Then, if you declare Brands as Form1 class field, then in the

private void buttonAddbrand_Click(object sender, EventArgs e)
{
    //Brands will be recognized
}

Brands will be recognized. If what you need to do is adding something to array (and you must use array). Then you should also preserve the number of the element in the current array like this:

public partial class Form1 : Form        
{

    string[] Brands = new string[10] { "Yamaha", "Suzuki", "Harley", "Kawasaki", "", "", "", "", "", "" };
    int brandNo = 4;

Then, when you add new item to the array, do it like this:

private void buttonAddbrand_Click(object sender, EventArgs e)
{
    if(brandNo >= 10)
        return; //cannot add more brand
    Brands[brandNo++] = "NewBrand"; //at the brandNo AFTER you put "NewBrand", see post-increment.
}

Edit:

As for the array initialization in the constructor, this is how your teacher wants - It is of longer method actually. But for the sake of teaching, I will just show it nevertheless:

public partial class Form1 : Form        
{
    string[] Brands = new string[10];
    int brandNo; //This is a must
    public Form1(){
        InitializeComponent();
        Brands[0] = "Yamaha"; //ok
        Brands[1] = "Suzuki"; //ok
        Brands[2] = "Harley"; //ok
        Brands[3] = "Kawasaki"; //ok
        brandNo = 4; //This is a must
    }

Answer 3

Ian's answer is a good one, it means you check if there is space and allows you to know where the space is.

An alternative, could be to not use an array, but instead use a list.

With a list you could do the following:

List<string> Brands = new List<string> { "Yamaha", "Suzuki", "Harley", "Kawasaki" };

Then in your add you can simply do:

private void buttonAddbrand_Click(object sender, EventArgs e)
{
    if(Brands.Count >= 10)
        return; //cannot add more brand
    Brands.Add("NewBrand");
}

I believe (please someone correct me if I'm wrong) there is a slightly bigger memory overhead with a List but personally I prefer to use them over arrays where I can.