如何使用C＃单击MDI中的另一个子窗体以关闭上一个子窗体

Question

I have a mdi parent form and I open my other forms in run time as mdi child form by this code:

private void winAppToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Upload objWA = new Upload();
            objWA.MdiParent = this;
            objWA.Show();
            //objWA.WindowState = FormWindowState.Maximized;
        }

        private void userInfoToolStripMenuItem_Click(object sender, EventArgs e)
        {
            Reports objUI = new Reports();
            objUI.MdiParent = this;
            objUI.Show();
            //objUI.WindowState = FormWindowState.Maximized;
        }

but the problem is: When current form is open, user can open another form and it can be repeated several times so that each form is opened what's code for closing the previous child form before user open a new child form??

Screen shot for reference if we see the image my upload and reports forms both are getting opened on one another but it should only show the currently opened form

Answer 1

public void DisposeAllButThis(Form form){
foreach (Form frm in this.MdiChildren)
{
    if (frm.GetType() == form.GetType() 
        && frm != form)
    {
        frm.Dispose();
        frm.Close();
    }
}}

got this from: C# loop through all MDI childer and close all other forms except the current

Answer 2

private void winAppToolStripMenuItem_Click(object sender, EventArgs e)
    {
        Upload objWA = new Upload();
        objWA.MdiParent = this;
        objWA.Show();
        //objWA.WindowState = FormWindowState.Maximized;
    }

    private void userInfoToolStripMenuItem_Click(object sender, EventArgs e)
    {
        Reports objUI = new Reports();
        objUI.MdiParent = this;
        objUI.Show();
        DisposeAllButThis(Form objUI);
        //objUI.WindowState = FormWindowState.Maximized;
    }
    public void DisposeAllButThis(Form form)
    {
        foreach (Form frm in this.MdiChildren)
        {
            if (frm.GetType() == form.GetType() 
                && frm != form)
            {
                frm.Dispose();
                frm.Close();
            }
        }
    }

let me know if it worked because i just made it up