The COM client and server can communicate with each other in three ways – vtbleinterfaces, dispinterface or dual interface. If the component is to be used only from compiled languages

When you declare a class as final, it can no longer be subclassed. Java has used this for security purposes with classes like String and Integer. It also allows the

An interface describes the public methods that a class should implement along with the calling conventions of those methods. An Interface says nothing about implementation of its methods. In essence,

When you declare a class as abstract, it cannot be instantiated. Only subclasses of an abstract class can be instantiated if they are not abstract themselves. When you declare a

When you synchronize a method of a class, as in: public synchronized int getAge(){ …} that method will acquire a monitor lock before execution. If the synchronized method is static,

When you declare a field variable of a class as static, that field variable is instantiated only once, no matter how many instances of the class are created. In other

Question: What is the best source, print or online, for learning how to implement persistence in C++? I want to save my objects to disk and restore them, and I

Question: I am using SQL Server 6.5 for my database needs and Visual C++ as a front-end. The problem is that sometimes when I switch on the server (where the

Question: Can I use ADO-connected recordsets with MTS? From the information I can find it seems that MTS does not handle them. Answer: You can, but the question is, do

Question: How does Spy++ make the borders of a window blink when you select “Highlight” from the right-click menu? I have a MouseProc in the hook chain, so I can

Question: I am a young programmer trying to learn C++. I have finished the three books that I own, but none of them cover queues or stacks. I have searched

Question: How do I redirect the output of a SQL query to a file? Answer: Use the isql command-line switches to redirect the output of a query to a file.

Question: I have a query that retrieves a field which is a foreign key in two tables. The tables are organization_name and person_name. Each instance of the foreign key is

Question: I want to show my users when a record was last updated. Is there any way to display the timestamp field? Answer: The timestamp field is not a good

Question: How do I take a SQL 6.5 database that is residing on one machine and move the entire database to another machine? Answer: I have three methods for you

Question: I’m running Windows NT 4.0 (Service Pack 3) and have developed an ActiveX Server (EXE) using Visual Basic 6 (Service Pack 3). How come whenever I try to create

Question: I have scoured the Web and can’t find any information on where to obtain BIOS version/name information. As far as I can tell, there are no APIs or C

Question: From the code below, I get output: ‘asdf’ which is correct. But when the VB program is closed, it says VB6 has preformed an illegal operaton and will be

After upgrading your system to FrontPage 2000, you may get an error message when you try to run the FrontPage Server Administrator from the Windows NT Option Pack group. The

It is useful to follow these guidelines when you develop COM components that need to talk to VB. 1. Only use VARIANT data types in your interface . Although VB

Because GUID are 16 bytes in size, you don’t want to pass them by value. Instead, you should pass them by reference. This is why Queryinterface takes a constant reference.

You can experience a great increase in database performance if you utilize connection pooling. Creating a connection to a database takes a lot of time and resources. If every you

‘ the name of a control given the corresponding VBControl object’ (accounts for items in control arrays)Function VBControlName(vbc As VBIDE.VBControl) As String Dim index As Long index = vbc.Properties(“Index”) If

‘ Returns the nesting level of a TreeView’s Node object’ (returns zero for root nodes.)Function NodeNestingLevel(ByVal Node As Node) As Integer Do Until (Node.Parent Is Nothing) NodeNestingLevel = NodeNestingLevel +

Every now and then you need to fill a TreeView control with some random data, for example when you want to test a routine and you don’t want to write

‘ Convert to uppercase, lowercase, or propercase the text that is’ currently selected in the active code windowSub ConvertSelectedText(VBInstance As VBIDE.VBE, Optional conversion As Long = _ vbUpperCase) Dim startLine

‘ Returns a value >0 if Node1 is a parent (or grandparent) of Node2’ Returns a value