c# - I would like to close a child form from another child forms event? -

i have child pops display data.

but when data changes new form created display new data.

i want close old form, don't end 5000 forms every time data changes.

the reason new form created in name data's id can shown.

my code:

string pass; // used value class , pass next form.  public void shownewcomparediff() //object sender, eventargs e {     formcomparediff childform = new formcomparediff(pass);     childform.mdiparent = mdiparent;     childform.text = "comepare difference ";      //childform.close(); //not working      //childform = null; //not working      childform.show(); }  private void datagridviewresult_cellmouseclick(object sender, datagridviewcellmouseeventargs e) {     comparexml com = new comparexml();     pass = com.compare(richtextboxsql.text, richtextboxprevsql.text);     shownewcomparediff(); } 

child form formcomparediff:

namespace auditit_1 {     public partial class formcomparediff : form     {         string passed;         public formcomparediff(string pass)         {             passed = pass;             this.startposition = system.windows.forms.formstartposition.manual;             this.location = new system.drawing.point(836, 0); // form shows next formschemasearch             initializecomponent();         }         private void formcomparediff_load(object sender, eventargs e)         {             string pass = passed;             comparexml com = new comparexml();             webbrowserdifferences.documenttext = com.resultshow(pass);         }            }     } 

you convert childform member variable of class, , alter shownewcomparediff method this:

formcomparediff childform;  public void shownewcomparediff() {     if (childform != null)         childform.dispose(); // rid of old form, if exists      childform = new formcomparediff(pass);     childform.mdiparent = mdiparent;     ... } 

edit:

complete example

create new windowsformapplication, add new button form, add following code:

public partial class form1 : form {     form myform;      public form1()     {         initializecomponent();     }      private void button1_click(object sender, eventargs e)     {         if (myform != null)             myform.dispose();          myform = new form() { text = datetime.now.tostring() };         myform.show();     } }         

test it. you'll see how works.