MFC Interview Preparation Guide

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No there wont be any difference. Infact the first method is
preffered

using SetWindowText()function we can change text of
specified window dynamically

In general, TargetObject is the object where you will get
the sorted result.

If you want to specific answer please update the context
and details of question like Grid or Array

BY USING THE TOOL TIP PROPERTY WE CAN KNOW THE WHERE THE
MOUSE POINT IS LOCATED NOW.

Using DoModal() function.
create a class of another dialog box.
and write a code in fist dialog box function.

Classname(second) variable_name;
variable_name.DoModl();

and define the new header file in fisrt dialog bob code.
like;
#include "classname.h"

int CALLBACK WinMain(
__in HINSTANCE hInstance,
__in HINSTANCE hPrevInstance,
__in LPSTR lpCmdLine,
__in int nCmdShow
);

1. Create a Object from CButton control. CButton m_ctlButton
2. m_ctlButton.Create("OK",ES_CHILD|ES_VISIBLE,CRect(0,0,100,100),CWnd*
pParentWnd,MB_OK);

with this we can create the button by dynamically.

Message map is dynamic function locater
It can look each function if it defined

e.g

void OnWndMessage(UINT message, WPARAM wParam, LPARAM
lParam, LRESULT *pResult)

{
// function looking MESSAGE_MAPS ((DECLARED))
// if found, CWnd::OnSize(UINT nStyle, int cx, int cy);
__thisclass.OnSize(wParam, HIWORD(lParam), LOWORD(lParam);
}
//M

new container
polymorphic wrapping
expression passing
Smart Pointer

1.Application Framework: The MFC library framework includes its own application structure-one that has been proved in many software environments.App wizard generates skeleton code for your entire application, and class wizard generates prototypes and function bodies for message handlers.
2.Message Mapping
3.Runtime class information
4.Serialization

Brush *brush;
Initialize the brush pointer in the constructor of your Dialog
Code:
brush = new CBrush(RGB(49,49,49));
Add the WM_CTLCOLR Message handler for the dialog and add the following code
Code:
switch (nCtlColor) {

case CTLCOLOR_BTN:
pDC->SetTextColor(RGB(0, 255, 0));
pDC->SetBkColor(RGB(0, 0, 0));
return (HBRUSH)(brush->GetSafeHandle());
default:
return CDialog::OnCtlColor(pDC, pWnd, nCtlColor);
}

DECLARE_SERIAL is super set for other 2 macros since The
DECLARE_SERIAL macro includes all the functionality of
DECLARE_DYNAMIC and DECLARE_DYNCREATE.

class myframe:public CFrameWnd
{
public:
myframe()
{
Create(NULL,"My Paint application");
}
void OnPaint()
{
CPaintDC d(this);
CBrush mybrush(RGB(0,255,0));
d.SelectObject(&mybrush);
d.Rectangle(50,150,150,50);
}
DECLARE_MESSAGE_MAP()
};
BEGIN_MESSAGE_MAP(myframe,CFrameWnd)
ON_WM_PAINT()
END_MESSAGE_MAP()
class myapp:public CWinApp
{
public:
int InitInstance()
{
myframe *p=new myframe;
p->ShowWindow(1);
m_pMainWnd=p;
return 1;
}
};
myapp a;

CCmdTarget class used to process window message, any class directly or indirectly inherited from CCmdTarget will eligible for message handling..

CString, CSize, CPOint..

primitive & non-primitive type are difference thing,primitive is the well defined data,we can't modified this type of data,but in non-primtive type as a user defined of data which store reference or object data,bcz they are created rather then per-defind

CObject is the base class for all the MFC classes.

There many ways to find memory leaks, One of the ways is by
using MFC class. And another way is using Purify tools...

CMemorState is a MFC class by which we can find the memory
leaks. Below is a sample code to find the same.

#ifdef _DEBUG
CMemoryState oldState, newState, diffState;
oldState.Checkpoint();
#endif
int* a = new int[10];
#ifdef _DEBUG
newState.Checkpoint();
if(diffState.Difference(oldState, newState))
{
TRACE0("Memory Leaked");
}
#endif

Instead of SendMessage API i will use the SendMessageTimeout
API to solve the system hang or You can use PostMessage API instead.

First, need to find the handle of the Control by using some API like EnumWindows and enumerrating all windows and checking for the text of the window by GetWindowTExt.
Once, handle of the target control has been identified, SendMessage can be used to send appropriate message to the control. like WM_SETTEXT can be sent to change text of window, etc...

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