How to pass values between forms in c# windows application?

Question

I have two forms A and B. Form A is the default start up form of the application. I do some stuffs in Form A and i then i want to run my Form B parallel and then pass a para

Answer 1

FormA should construct/hold an instance to FormB. Obviously the method on FormB needs to be public, change the type of object used in CallMethodOnFormB to the correct type too.

public class FormA
{
   private FormB fB;

   public void CreateFormB()
   { 
      // This shows the form in parallel.
      this.fB = new FormB();
      this.fB.Show();
   }

   public void CallMethodOnFormB(object value)
   {
      this.fB.RunSomeFunction(value);
   }
}