why myDiagl subclassed from CDialg don't have destructor?

[C++ Programming]

Hi,

I'd like to know,,.

1) when I create my Dialog from CDialog class, why my Dialog does not have Destrucotr?
I want to free some heap memory I used in program,,, when I write writ memory clear code?


2) class CMyView
{
//from somewhre(such as thread) can
FuncA() {A();}

//from somewhre(such as thread) can send Window Message via (SendMessage())
FuncB(WPAAM w, LPARAM l) { A();}


A(){ print("A() called"); }
}

I'd like to know How they are diffrent?
when from calling function and calling via SendMessage()?


Have a day.