Both C and C++ enable you to store and access data directly in the tiniest possible unit: a bit. This technique is required when dealing with a huge amount of

Dynamic binding, for example, having a virtual member(s), is one of the basic principles of OO programming. If the compiler can resolve a call to a virtual member function statically,

Once declared virtual, a member function can be overridden in any level of derivation, as long as the overriding version has the identical signature of the original declaration. This is

The C/C++ register keyword can be used as a hint to the compiler that the declared variable is to be accessed very often during program execution, and hence, should be

An object’s member functions (both virtual and non-virtual) can be called from its constructor. The invoked virtual is guaranteed to be the one defined in the current object (or higher,

A static member function in a class can access only other static members of a class or variables which are not members of its class. It can be invoked even

C++ supports Run-time Type Identification (RTTI), which enables detection of actual object type during program execution using the built-in typeid() operator. Here is an example: //file: classes.hclass base{ base(); virtual

In object-oriented programming (OOP), global objects are considered harmful. Particularly in C++, there’s even more reason to think twice before using them: a global object construction occurs before a program’s

A const member or a reference member cannot be initialized within an object’s constructor. Instead, they must be initialized in the constructor’s member-initializer list. Conceptually, mem-initialization takes place before the

Unions are used to minimize memory waste. For example, consider the following database-transaction class used to update a person’s data. The key can be either a unique ID number or

Question: How can I get the Windows 95 print dialog box todisplay instead of the print setup dialog usingprintsetup()? Answer: You have to build your own custom dialog window. The

Question: I have been reading Visual C++ 5 in 21 Days while trying to learn how to use the Visual C++ user interface, and I have been trying to find

Question: Is there a way for me to issue system commands (for example, DOS commands: dir, md temp, etc.) from within a C++ program? Answer: You can use the C

Question: When I use Windows API functions in PB, the null-terminate string is often needed. For example, when I use GetSaveFileName,the parameter lpstrFilter is really a trouble to me. Please

Question: I am trying to get an image change script to be downward compatible, but Internet Explorer 3.0 does not recognize MouseOvers. Is there another way to do an image

Question: I’m developing a VB program that requires manipulation of pictures. I can read them in and display them without any problem, but I have no way (that I can

Question: What is the most cost-effective engine and method for licensing clients in client/server applications? Answer: For PowerBuilder applications, the runtime license for clients is free. You can have a

Question: If I have an abstract base class with a pure virtual function called get_data(), how do I declare the function in inherited classes to have different return types than

Question: I would like to know if there are any PB import utilities that can import Excel files into a datawindow, datastore, or database table. Answer: PowerBuilder 6 can import

Question: Which versions of PowerBuilder are year 2000 compliant? Answer: PB5.0.4 is year 2000 compliant. All versions before that release had a few minor problems that would not affect most

Question: How can you tell if blob1 = blob2? Answer: You can just use: IF blob1 = blob2 THEN I have used this in the past to compare bitmaps to

Question: What are the issues involved, if any, if your development environment uses Windows NT and you want to deploy the application to a Windows 95 environment? Answer: There are

Question: I am looking for a way to display an arrowin the the “sorted column” heading to indicatethe direction and column sorted. This functionality can be seen in MS-Exchange. Answer:

Question: Can I change the font size of the ToolBar text for the application (not the development painters)? Answer: No. The font size is taken from the user’s operating system

Question: How can I scale down a DW object? Why is the DW object Ruler inch size much bigger than a real inch size? Answer: You can scale a datawindow

Question: I am a rookie at PowerBuilder. I use PB 5, and I can’t seem to find a function that reads a specific number of chars from a file into

Question: How do I get the application directory for a PB5-16 app? Answer: You can use the API call GetCurrentDirectory when your application starts to find out its home directory.

Question: I am trying to find some information on Unions in C++, specifically syntax and some type of example and perhaps a discussion as to when and why they are

Question: How can I control the draw order (i.e., BringToFront, SendToBack) of datawindow objects dynamically created in the deatil band? Answer: At design time you can layer objects by using

Question: I can compile all of my .cpp files (they were written by my teacher), but I get error messages when I try to run them. I get a make