How to pass values ​​between forms?

Question

Programming

Good afternoon. There are two forms

Form1 with value1 variable
Form2 with value2 variable

The problem is that value1 is not set immediately, but during code execution, and when declaring an instance of Form1 in the constructor for Form2, an error is generated.
How to pass value1 to Form2 and value2 to form1?
As I understand it, the second form is created at startup earlier than the first, and therefore the class declaration does not work?

Answer 1

Use the "parent" property

/* в родительской форме */
Form2 f = new Form2();
f.Owner = this;
f.ShowDialog();

/* в дочерней форме */
Form1 main = this.Owner as Form1;
if(main != null)
{
    string s = main.textBox1.Text;
    main.textBox1.Text = "OK";
}