How to create more than 1 object in C#?

Question

I want to create more than 1 TextBox in my application.

My code bellow only creates one TextBox because I create a global object.

My code to do this:

private Label ctrLabel = new Label();

public void btnAddCharacter_Click(object sender, EventArgs e)
{
    String LableName = "Lbl_";
    ctrLabel.Name = LableName;
    ctrLabel.Text = txtIDImg.Text;
    panel2.Controls.Add(ctrLabel);
}

If put Label ctrLabel = new Label(); inside the event btnAddCharacter_Click it will be create multiple object. But all control using ctrLabel will error because it doesn't know ctrLabel. The problem is: in other control of Winform will be using and manipulation with this object.

So, I don't know when user click text 1 or text 2, etc.. to apply a change to the corresponding with event like: cbxFontSize_SelectedIndexChanged, cbxFont_TextChanged, etc .....

My code like this:

private void cbxFontSize_SelectedIndexChanged(object sender, EventArgs e)
{
    ctrLabel.Font = new Font(ctrLabel.Font.FontFamily, Convert.ToInt32(cbxFontSize.SelectedItem),
        ctrLabel.Font.Style);
}

private void cbxFont_TextChanged(object sender, EventArgs e)
{
    ctrLabel.Font = new Font(cbxFont.Text, ctrLabel.Font.Size, ctrLabel.Font.Style);
}

and much other control will change a property of an object(TextBox).

teynon · Accepted Answer · 2016-05-07 03:52:32Z

2

It's hard to tell exactly what you are trying to do here, but if you want to manage multiple Labels that are created dynamically, you should maintain them using a list. I.E. like below (not tested code)

List<Label> activeLabels = new List<Label>();

private void CreateLabel() {
    Label ctrLabel = new Label();
    String LableName = "Lbl_" + activeLabels.Count();
    ctrLabel.Name = LableName;
    ctrLabel.Text = txtIDImg.Text;
    panel2.Controls.Add(ctrLabel);
    activeLabels.Add(ctrLabel);
}

private Label GetLabel(int index) {
    if (index > 0 && index < activeLabels.Count())
        return activeLabels[index];

    return null;
}

answered May 7, 2016 at 3:52

teynon

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Joel Coehoorn · Accepted Answer · 2016-05-07 03:58:24Z

private Label SelectedLabel; //don't initialize here (also note the name change)

public void btnAddCharacter_Click(object sender, EventArgs e)
{
    //do it here:
    var ctrLabel = new Label();
    ctrLabel.Name = "Lbl_";
    ctrLabel.Text = txtIDImg.Text;
    ctrLabel.BackColor = Color.Transparent;

    // In each of these events, add a line at the very top that looks like this:
    //     var ctrLabel = sender as Label;
    ctrLabel.MouseEnter += new EventHandler(control_MouseEnter);
    ctrLabel.MouseLeave += new EventHandler(control_MouseLeave);
    ctrLabel.MouseDown += new MouseEventHandler(control_MouseDown);
    ctrLabel.MouseMove += new MouseEventHandler(control_MouseMove);
    ctrLabel.MouseUp += new MouseEventHandler(control_MouseUp);

    panel2.Controls.Add(ctrLabel);
}

// Somewhere (perhaps in the events above) you have code that decides
// which control is selected. Now, instead of `ctrLabel`, you track this
// assigning to the `SelectedLabel` variable. Then the two methods below
// can look like this:
private void cbxFontSize_SelectedIndexChanged(object sender, EventArgs e)
{
    if (SelectedLabel == null) return;
    SelectedLabel.Font = new Font(ctrLabel.Font.FontFamily, Convert.ToInt32(cbxFontSize.SelectedItem),
        SelectedLabel.Font.Style);
}
private void cbxFont_TextChanged(object sender, EventArgs e)
{
    if (SelectedLabel == null) return;
    SelectedLabel.Font = new Font(cbxFont.Text, SelectedLabel.Font.Size, SelectedLabel.Font.Style);
}

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