Problem displaying modal child dialogs

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C++

MFC

UI

dialog

My project is a MFC project based on dialogs. The class name of my parent dialog is CdialogchangDlg and my child dialogs are CPicture2 and CPicture3. I can access my child dialogs. Now I want to go to another child dialog from one child dialog, I use buttons to do this.

The code is:

void CPicture2::OnBnClickedButton1()
{
	CPicture3 pic3;
	OnOK();
	pic3.DoModal();
}

and

void CPicture3::OnBnClickedButton1()
{
	CPicture2 pic2;
	OnOK();
	pic2.DoModal();
}

The program runs without problems. But when I click the button about 300 times to change dialog box between the two child dialogs the program is dead. When I click the button, I find the internal memory gave to the program go up with no stop until the program is dead. Some people said when I use DoModal() the current dialog is not really destroyed. Is that true? And how could I resolve this problem?
I am a freshman, thank you.