TweetFollow Us on Twitter

Feb 95 Top 10
Volume Number:11
Issue Number:2
Column Tag:Think Top 10

Think Top 10

This monthly column, written by Symantec’s Technical Support Engineers, aims to provide you with technical information based on the use of Symantec products.

By Mark B. Baldwin and Steve Howard, Symantec Technical Support

Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.

Q. Why do I get bus errors when I create a CStyleText object by using the constructor with arguments?

A. In the process of upgrading the TCL, constructors with arguments were added to the classes. In this case, constructors with arguments do not create a new handle to a TERec, the macTE data member of the CStyleText object. To work around this, call the constructor with no arguments and call the IStyleTextX() method.

Q. I am having trouble using sizeof() with printf(). For example:

printf("char size is %d.", sizeof(char));

outputs "char size is 0." Why do I get the wrong result?

A. The output is wrong because the return value of the sizeof() function is a size_t (an unsigned long). Use an %ld rather than a %d as a format specifier. Thus, the correct syntax is

"printf ("The size of a char is %ld.", sizeof(char));" 

Q. How can I avoid problems deleting heap objects whose references are on the stack when using exception handling? The pointer (which is on the stack) to the object becomes invalid when the stack unwinds and only the destructors for automatic objects are guaranteed to be called when an exception is thrown.

A. To handle this, declare pointers as volatile. Last month we explained why you should use the volatile type. Below is a practical example. Use volatile file pointers so that stack unwinding does not reset the value of the pointer (prohibiting the file from being closed).

  funClass * volatile funClassPtr;    // Syntax for volatile declaration 
  funClassPtr = NULL;         // Pointer to NULL guarantees delete as safe.
  int myInt = 1;                      // Watch in debugger to see
                                      //   the stack unwind.
  try_ {
    funClassPtr = TCL_NEW(funClass, ());//macro for new operator
    myInt = 2;                          //put new value on stack
    Failure (2, 100);                   // Force exception 
  } 
  catch_all_() {                      //catch block
    
  delete funClassPtr;                 //this calls destructor.
     
     // myInt is reset to 1, delete removes the object from the  heap 
  }
  end_try_                            //end of try block

Q. How can I use exception handling without using the Think Class Library?

A. To use exception handling without the Think Class Library, include BRLib and Exceptions.cp in your project. Also, compile with the directive #define NO_TCL

The four macros used to make exception handling work correctly are:

  AUTO_DESTRUCT_OBJECT
  TCL_NEW
  TCL_END_CONSTRUCTOR
  TCL_START_DESTRUCTOR

The macro AUTO_DESTRUCT_OBJECT will guarantee that the destructor is called for an automatic object on the stack. A destructor will only work on a completely constructed object. TCL_END_CONSTRUCTOR helps the compiler to determine the complete construction of an object.

Here’s an example that shows how the macros are used.

class funClass TCL_AUTO_DESTRUCT_OBJECT //macro in class header  
{ 
public:
    funClass()  {                       // no arg constructor 
    cout<< "In constructor."<<endl;
    char * myStr = new char[64];        // allocate memory 
    TCL_END_CONSTRUCTOR                 // End of the constructor
    }
    virtual ~funClass() {               // virtual destructor 
    TCL_START_DESTRUCTOR                // Beginning of the destructor 
    cout<< "In destructor."<<endl;
    delete [] myStr;                    // deallocate memory 
    } 
};

Q. Where can I get the Quickdraw GX headers?

A. APDA has a Quickdraw GX Developer’s Kit which contains a CD with the electronic versions of Inside Macintosh for GX, headers, required system software components, and excellent examples which are compilable under THINK C or Symantec C++. For ordering information, call (800) 282-2732. [If all you need is the header files, check out the MacTech Magazine online sites. See page 2 for details - Ed stb]

Q. When I build an application with the TCL, the application does not seem to be scriptable. How can I make it scriptable?

A. The default flags for the SIZE Resource of the application are set to not receive Background NULL Events. Make sure that the flags for your application have this bit turned on.

Q. I have a program that I’m converting from DOS and would like to be able to draw some simple graphics to the console window. How can I do that?

A. Don’t do it. If you draw to the console window, you will not receive update events. However, if you just can’t help yourself from going down this path, here is how to do it.

 #include <iostream.h>
    
 WindowPtr myWindow;         // To be used for the console window.
     
 void main (void)    {    
   cout << " ";                //A simple way to show the console.
   myWindow = FrontWindow();   //Get a pointer to the console.
   SetPort(myWindow);          //Set the port for drawing.
   PenNormal();                //Set the pen for drawing.
   LineTo(100,47);             //Draw a line.     
 }

Q. If I am mixing C and C++ code, should I turn on the option to use Native Floating Point format?

A. Yes. Symantec’s C++ compiler is using the Native Floating Point format. To make sure that your floating point calculations give you the expected results, turn on Use Native Floating Point in the options for the C compiler.

Q. Will Symantec be updating the THINK Reference Databases?

A. Yes. THINK Reference is undergoing a massive overhaul. It will be updated for the Universal Headers and the Think Class Library, and will include new databases for C++ Error Messages. As before, references will be hyperlinked for easy access to information.

Special thanks to: Craig Conner, Colen Garoutte-Carson, Rick Hartmann, Michael Hopkins, Scott Morison, Celso Barriga, Kevin Irlen, Yuen Li, and Chris Prinos.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Four apps to help improve your Super Bow...
Super Bowl Sunday is upon us, and whether you’re a Panthers or a Broncos fan you’re no doubt gearing up for it. [Read more] | Read more »
LooperSonic (Music)
LooperSonic 1.0 Device: iOS Universal Category: Music Price: $4.99, Version: 1.0 (iTunes) Description: LooperSonic is a multi-track audio looper and recorder that will take your loops to the next level. Use it like a loop pedal to... | Read more »
Space Grunts guide - How to survive
Space Grunts is a fast-paced roguelike from popular iOS developer, Orange Pixel. While it taps into many of the typical roguelike sensibilities, you might still find yourself caught out by a few things. We delved further to find you some helpful... | Read more »
Dreii guide - How to play well with othe...
Dreii is a rather stylish and wonderful puzzle game that’s reminiscent of cooperative games like Journey. If that sounds immensely appealing, then you should immediately get cracking and give it a whirl. We can offer you some tips and tricks on... | Read more »
Kill the Plumber World guide - How to ou...
You already know how to hop around like Mario, but do you know how to defeat him? Those are your marching orders in Kill the Plumber, and it's not always as easy as it looks. Here are some tips to get you started. This is not a seasoned platform... | Read more »
Planar Conquest (Games)
Planar Conquest 1.0 Device: iOS Universal Category: Games Price: $12.99, Version: 1.0 (iTunes) Description: IMPORTANT: Planar Conquest is compatible only with iPad 3 & newer devices, iPhone 5 & newer. It’s NOT compatible with... | Read more »
We talk to Cheetah Mobile about its plan...
Piano Tiles 2 is a fast-paced rhythm action high score chaser out now on iOS and Android. You have to tap a series of black tiles that appear on the screen in time to the music, being careful not to accidentally hit anywhere else. Do that and it's... | Read more »
Ultimate Briefcase guide - How to dodge...
Ultimate Briefcase is a simple but tricky game that’s highly dependent on how fast you can react. We can still offer you a few tips and tricks on how to survive though. Guess what? That’s exactly what we’re going to do now. Take it easy [Read more... | Read more »
SoundPrism Link Edition (Music)
SoundPrism Link Edition 1.0 Device: iOS Universal Category: Music Price: $4.99, Version: 1.0 (iTunes) Description: ***Introductory price for a the first few days after launch - if you're reading this, get it while it's fresh out of... | Read more »
Pre-register now for hack and slasher An...
Fincon, which won Facebook's Studio to Watch award in 2015, has announced that pre-registration is now open for the massive 3.0 update for its award-winning hack and slasher Angel Stone. Angel Stone is a post-apocalyptic action RPG in which the... | Read more »

Price Scanner via MacPrices.net

Apple refurbished 2014 13-inch Retina MacBook...
Apple has Certified Refurbished 2014 13″ Retina MacBook Pros available for up to $400 off original MSRP, starting at $979. An Apple one-year warranty is included with each model, and shipping is free... Read more
Macs available for up to $300 off MSRP, $20 o...
Purchase a new Mac or iPad using Apple’s Education Store and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free, and... Read more
Watch Super Bowl 50 Live On Your iPad For Fre...
Watch Super Bowl 50 LIVE on the CBS Sports app for iPad and Apple TV. Get the app and then tune in Sunday, February 7, 2016 at 6:30 PM ET to catch every moment of the big game. The CBS Sports app is... Read more
Two-thirds Of All Smart Watches Shipped In 20...
Apple dominated the smart watch market in 2015, accounting for over 12 million units and two-thirds of all shipments according to Canalys market research analysts’ estimates. Samsung returned to... Read more
12-inch 1.2GHz Retina MacBooks on sale for up...
B&H Photo has 12″ 1.2GHz Retina MacBooks on sale for $180 off MSRP. Shipping is free, and B&H charges NY tax only: - 12″ 1.2GHz Gray Retina MacBook: $1499 $100 off MSRP - 12″ 1.2GHz Silver... Read more
12-inch 1.1GHz Gray Retina MacBook on sale fo...
B&H Photo has the 12″ 1.1GHz Gray Retina MacBook on sale for $1199 including free shipping plus NY sales tax only. Their price is $100 off MSRP, and it’s the lowest price available for this model... Read more
Apple now offering full line of Certified Ref...
Apple now has a full line of Certified Refurbished 2015 21″ & 27″ iMacs available for up to $350 off MSRP. Apple’s one-year warranty is standard, and shipping is free. The following models are... Read more
Free GUI Speedometer – The Ultimate Digital D...
Miami, Florida based RMKapps has announced the official release of GUI Speedometer 1.0, their digital dashboard display developed for iOS devices. GUI Speedometer allows users to track their precise... Read more
FutureCalc: Ergonomic iOS Calculator App For...
London, United Kingdom based Independent software developer and entrepreneur, Hovik Melikyan has announced the release and immediate availability of FutureCalc 1.0, his new ergonomic calculator app... Read more
Save up to $600 with Apple refurbished Mac Pr...
Apple has Certified Refurbished Mac Pros available for up to $600 off the cost of new models. An Apple one-year warranty is included with each Mac Pro, and shipping is free. The following... Read more

Jobs Board

*Apple* Subject Matter Expert - Experis (Uni...
This position is for an Apple Subject Matter Expert to assist in developing the architecture, support and services for integration of Apple devices into the domain. Read more
*Apple* Macintosh OSX - Net2Source Inc. (Uni...
…: * Work Authorization : * Contact Number(Best time to reach you) : Skills : Apple Macintosh OSX Location : New York, New York. Duartion : 6+ Months The associate would Read more
Computer Operations Technician ll - *Apple*...
# Web Announcement** Apple Technical Liaison**The George Mason University, Information Technology Services (ITS), Technology Support Services, Desktop Support Read more
Restaurant Manager - Apple Gilroy Inc./Apple...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
Simply Mac *Apple* Specialist- Service Repa...
Simply Mac is the largest premier retailer of Apple products in the nation. In order to support our growing customer base, we are currently looking for a driven Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.