Finding the parent'control

Question

Hello ,
i am trying to find out the label control on the parent form and set its text property from the child form . to do this , i had tried many approaches and even set the modifier of that label to public but still can't access it . pls correct my code .

  public partial class login : blackborder_lightform
    {
        public login()
        {
            InitializeComponent();
        }

        private void login_Load(object sender, EventArgs e)
        {
            // Access the parent form
           // Form parent = (Form)this.Owner;   
         //  Label label = this.Parent.Labels["Label1"];
            parent.CurrentForm.Text = "Login Form is in focus "; 
            label1.Text += "Dummy";
            this.ActiveControl = textBox1;
        }

Answer 1

Form parent = (Form)this.Owner;
Label label = parent.Controls.Find("Label1", true)[0] as Label;

see also: https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.control.controls
https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.control.controlcollection
https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.control.controlcollection.find

Answer 2

Although you have an answer there is a better way using a delegate/event. This way there is zero need to find the label.

Take sometime to learn about delegates/events as they extremely helpful in more ways than shown below. Also note, in the code below I pass a string, you can pass anything you want like an instance of a class or a number, bool etc.

In regards to subscribing to events, check out Microsoft docs How to subscribe to and unsubscribe from events (C# Programming Guide)

Child form

public partial class Form2 : Form
{
    public delegate void ChangeLabelText(string sender);
    public event ChangeLabelText OnChangeLabelText;
    public Form2()
    {
        InitializeComponent();
    }

    private void UpdateButton_Click(object sender, EventArgs e)
    {
        OnChangeLabelText!.Invoke(textBox1.Text);
    }
}

Parent form, in a button click event

private void button3_Click(object sender, EventArgs e)
{
    Form2 form2 = new Form2();
    form2.OnChangeLabelText += Form2_OnChangeLabelText;
    form2.Show();
}

private void Form2_OnChangeLabelText(string sender)
{
    label1.Text = sender;
}