Question

I have two windows forms.Now I have to close first one and show the second form and vice-versa.How can i do it.I was passing this pointer to the constructor of second form and then trying to
close it,but this did not work.I can not use showdialog here.

Answer 1

Add static variables to each form in the Program class:

static class Program
{
    public static Form1 f1=null;
    public static Form2 f2 = null;

    public static FullClose=false;

    /// <summary>
    /// The main entry point for the application.
    /// </summary>
    [STAThread]
    static void Main()
    {
        Application.EnableVisualStyles();
        Application.SetCompatibleTextRenderingDefault(false);

        f1=new Form1();
        f2 = new Form2();

        Application.Run(f1);
    }
}

Then in the Form_Closing event of each form:

private void Form1_FormClosing(object sender, FormClosingEventArgs e)
{
    if (Program.FullClose==false)
    {
       e.Cancel = true;
       this.Visible = false;

       Program.f2.Show();
    }
}

(Change Program.f2.Show() to Program.f1.Show() in Form2).

Of course this will stop the application from ever closing, so you should provide an extra button (or similar) that sets a boolean static variable (FullClose) that the Form_Closing events can check to see if they should properly close or not.