如何在mdi c中从父表单影响子表单＃

Question

My problem is that I have created child's object and show child first time. but when second time I just want to change value of child's label from parent but don't want to show another form. Here is my code.

First time

ChildForm ObjChild = new ChildForm("Hi");
ObjChild.Show();

On second time I just want to set Bye in place of Hi.

ChildForm ObjChild = new ChildForm("H!");
ObjChild.BringToFront();

Because child form is already opened. This is my child Form

public Form1(string p_Param)
{
InitializeComponent();
Label1.Text = p_Param;
}

Answer 1

Constructors call one time when object created. You must implement a new public void or function rather than a constructor to do that.

public void ChangeLabelText(string txt)
{
Label1.Text=txt;
}

EDIT:

In your parent form; Out of functions;

chilFrm ChildForm;

Inside any function;

if (chilFrm == null)
{
    chilFrm = new ChildForm();
    chilFrm.TopLevel = false;
    chilFrm.Parent = this;
    chilFrm.StartUpProsecc("Created New");
    chilFrm.Show();
}
else
{
    chilFrm.StartUpProsecc("Showed the existing.");
    chilFrm.BringToFront();
}