valu @ 不老歌 - 记录与分享

code :
public bool CheckChildFormExist(string ChildFormName)
{
foreach(Form ChildForm in this.MdiChildren)
{
if (ChildForm.Name == ChildFormName)
{
if (ChildForm.WindowState == FormWindowState.Minimized)
{
ChildForm.WindowState = FormWindowState.Normal;
}
ChildForm.Activate();
return true;
}
}
return false;
}

example :
...
if (!CheckChildFormExist("Form2"))
{
Form1 strForm1 = new Form1();
strForm1.MdiParent = this;
strForm1.Show();
}
...