如何在单击按钮时停止多次打开表单

Question

I would like help to make sure only one version of windows form is open each time the button is pressed on my main form, not an instance per button click My current code is:

private void button3_Click(object sender, EventArgs e)
{
    Login PassForm = new Login();
    if (!PassForm.Visible)
    {
        PassForm.Show();
    }
   /*
    else
    {
        PassForm.BringToFront();
    }
    */
}

I commented the part out because it isn't working

Answer 1

Keep the same instance, don't go creating a new one every time.

private Login _passForm = new Login();

private void button3_Click(object sender, EventArgs e)
{
    if (!_passForm.Visible)
    {
        _passForm.Show();
    }
    else
    {
        _passForm.BringToFront();
    }
}