WinForm A continuous Click button to open a form only once

Many friends, when learning C #, the production of WinForm small program always has a problem, if we set in the parent form is clicked a button, open a subform, continuous click always appear continuously the same form, but we sometimes just want to open a form, how to do?

Hehe, I come to tell you, I hope to help you, of course, I understand the mood of beginners, can read, to ensure that the code is available, I hope to help you.

//set the public method to open only once Public Static intCXYPX (Form Frmmdifather,stringstrmdichild) {            intBreturn =-1;  for(inti =0; i < frmMdiFather.MdiChildren.Length; i++)            {                if(Frmmdifather.mdichildren[i]. Name = =strmdichild) {Frmmdifather.mdichildren[i].                    BringToFront (); Breturn=i;  Break; }            }            returnBreturn; }

//then add the following code to your button click event:Private voidAdd Billing Toolstripmenuitem_click (Objectsender, EventArgs e) {            intindex = CXYPX ( This,"ZD");//Remember, the ZD here is the name of the subform.            if(Index = =-1) {ZD tjzb=NewZD ();//Tjzb is an instance of a subform, and It's a place to change.Tjzb. MdiParent = This; Tjzb.            Show (); }            Else            {                 This. Mdichildren[index].            Show (); }        }

WinForm A continuous Click button to open a form only once