CPen error!!!

This is a discussion on CPen error!!! within the Windows Programming forums, part of the Platform Specific Boards category; I used the following code in my Paint program Code: switch (flag) { case 1: //drawing freehand CPen *penBlack,*newpen; // ...

  1. #1
    Registered User
    Join Date
    Nov 2002
    Posts
    42

    CPen error!!!

    I used the following code in my Paint program

    Code:
    switch (flag)
    	{
    		case 1:
    			//drawing freehand
    			CPen *penBlack,*newpen;  // Construct it, then initialize
                  if( newpen->CreatePen( PS_DOT, 2, RGB(255,0,0) ) )
                   {
                     // Select it into the device context
                     // Save the old pen at the same time
    				   penBlack = pDC->GetCurrentPen();
    				   pDC->SelectObject( newpen );
                   
    			if (nFlags && MK_LBUTTON)
    				{
    			    pDC->MoveTo (OldPoint.x, OldPoint.y);
    				pDC->LineTo (point.x,point.y);
    				}
    				// Restore the old pen to the device context
                    pDC->SelectObject( penBlack );
    			   }
                    break;
    In fact a good deal of it is from http://msdn.microsoft.com/library/de...ce_context.asp
    But although it compiles fine, when i try to run it, it gives me the following error message

    The instruction [-some number-] read memory address [0x....] which could not be read.

    What does this mean ???

  2. #2
    Registered User
    Join Date
    May 2003
    Posts
    148
    Code:
    CPen *penBlack,*newpen;  // Construct it, then initialize
     if( newpen->CreatePen( PS_DOT, 2, RGB(255,0,0) ) )
    You say it,but you don't do it.
    newPen points to nirvana,and the CPen Object is not constructed.
    You have to call new on it
    Code:
    newPen = new CPen(... //Don't know which parameter

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