C＃-数组-输入名称并显示它们

Question

here is my code that works.

1. Except after hitting Show Names button (after entering names) that stored in Array, display textbox scroll bar jump down and have to pull it up to see entered names.

2. Also, after I continue entering names(after entering few), I get line breaks (in show Names textbox) and entered names are shown repeated. It should display the names after the last entered one without repeating the previously entered names and line breaks.

Any ideas what is causing it?

my code:

namespace Arrays
{
public partial class frmMain : Form
{


    public frmMain()
    {
        InitializeComponent();
    }


    //initialize the Array
    string[] names = new string[100];

    int index = 0;


    //Enter  Names up to 100 and store them in array
    private void btnEnterName_Click(object sender, EventArgs e)
    {
        if (index < names.Length)
        {
            names[index++] += txtName.Text;
            txtName.Clear();
        }
        else
        {
            // array 'full'
        }
    }

    //Display stored Names in Array using foreach loop in multiline textbox
    private void btnShowNames_Click(object sender, EventArgs e)
    {
        txtName.Clear();
        foreach (string item in names)
        {
            txtNames.AppendText(item + Environment.NewLine);
        }
    }

}
}

Answer 1

For the scrollbar problem, setting the Text instead of using AppendText will resolve the issue:

//Display stored Names in Array using foreach loop in multiline textbox
private void btnShowNames_Click(object sender, EventArgs e)
{
    string allNames = "";
    foreach (string item in names)
    {
        allNames += item + Environment.NewLine;
    }
    txtNames.Text = allNames;

    // or more advanced
    //txtNames.Text = string.Join(names, Environment.NewLine);
}

Line breaks should happens if you hit the button without entering a name in it. Test the presence of the Text before adding it:

//Enter  Names up to 100 and store them in array
private void btnEnterName_Click(object sender, EventArgs e)
{
    // remove spaces at start and end
    string trimedName = txtName.Trim();
    bool nameExist = !string.IsNullOrEmpty(trimedName);
    bool notHittingMaxName = index < names.Length;
    if (nameExist && notHittingMaxName)
    {
        names[index++] += trimedName;
        txtName.Clear();
    }
    else
    {
        // array 'full' or empty name
    }
}