How to pass textbox data between two forms?

Question

How to send textbox value to textbox between two forms without Show()/ShowDialog() by button? I want to textBox will get value without open form.

Answer 1

To pass information from a parent from to a child form you should create a property on the child form for the data it needs to receive and then have the parent form set that property (for example, on button click).

To have a child form send data to a parent form the child form should create a property (it only needs to be a getter) with the data it wants to send to the parent form. It should then create an event (or use an existing Form event) which the parent can subscribe to.

An example:

namespace PassingDataExample
{
    public partial class ParentForm : Form
    {
        public ParentForm()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            ChildForm child = new ChildForm();
            child.DataFromParent = "hello world";

            child.FormSubmitted += (sender2, arg) =>
            {
                child.Close();

                string dataFromChild = child.DataFromChild;
            };

            child.Show();
        }
    }
}

namespace PassingDataExample
{
    public partial class ChildForm : Form
    {
        public ChildForm()
        {
            InitializeComponent();
        }

        public string DataFromParent { get; set; }

        public string DataFromChild { get; private set; }

        public event EventHandler FormSubmitted;

        private void button1_Click(object sender, EventArgs e)
        {
            DataFromChild = "Hi there!";

            if (FormSubmitted != null)
                FormSubmitted(this, null);
        }
    }
}