Form1:
Form2 fm2 = new Form2();
if (fm2.ShowDialog() == System.Windows.Forms.DialogResult.OK)
{
fm2.Close();
this.DialogResult = System.Windows.Forms.DialogResult.OK;
}
Form2(登录):
this.DialogResult = System.Windows.Forms.DialogResult.OK;
Form3(主窗体):
program:
Form1 f1 = new Form1();
if (f1.ShowDialog() == DialogResult.OK)
{
f1.Close();
Application.Run(new FormMain());//显示主窗体
}