C# 폼 상속

폼2 
 public partial class charextract : Form 
    { 
        Form1 f1; 
        public charextract(Form1 frm) 
        { 
            InitializeComponent(); 
            f1 = frm; 
        } 


폼1 
charextract frm = new charextract(this); 
            frm.Show();