devxlogo

The Latest

Netscape Displays a Blank Page

Question: My Web page works fine using Internet Explorer but if view with Netscape it displays a blank page. I think it has something to do with the table commands,

Make a Cursor Appear in First Form Field

Question: When designing a form, like a login page, how do I make the cursor automatically sit in the first form field? For example, I ask for an admin number

Pre-Fill a User Form

Question: I’d like to implement a script on my Web site that I’ve seen on other sites. This script asks visitors to register for free through a form as a

Delete an Item From Favorites

Question: How do I delete an item from Favorites under Windows NT 4.0? Answer: Under Windows NT 4.0, the favorites are saved in this folder: C:WINNTProfilesFavorites You can delete items

The Size of an Enum Type

In C, the size of an enumeration equals the sizeof(int). In C++, the underlying type for an enumeration is not necessarily an int–it can be smaller. Furthermore, if an enumerator’s

Invoking Methods Using Reflection

The java.reflect package enables a Java program to invoke methods on classes using the string names of the methods. This feature is the basis of the interaction between a Java

Start MS SQL Server Dynamically

Use this code in your C++ executable to start MS SQL Server dynamically on aWindows NT machine. Link to w95scm.lib, which is provided with the SQL 7.0 CD. #include “wn95scm.h”

Two Conundrums Associated With Inline Functions

Two conundrums are associated with inline functions. The first has to do with maintenance. A function can begin its life as a slim inline function, offering the benefits that are

Compiling a Large Number of Files With JDK 1.1

Using the javac utility provided with the Java Development Kit (JDK) 1.1.x to compile a large number of source files often fails with an OutOfMemoryError. To avoid this error, you

Concatenate to Increase ASP Performance

Although it is common to use repeated Response.Write statements in an Active Server Pages script, you may not be getting the most out of your Web server. Each time you

Passing a parameter to an external function

Question: Can I pass the address of a PowerBuilder function as an argument to an external function located in a dll? The dll documentation shows that it expects the address

64-bit integer support

Question: How can I support 64-bit integers on a 32-bit system? I need to do division on numbers exceeding 4.3 billion. I have the resaults in a char value, and

Copy objects

Question: Assume that you have a class Distance and two objects dist1 and dist2. You have initialized the object dist1. Now you do: Distance dist2(dist1) to create a copy of

Data Files Help

Question: I am teaching an introductory C++ course at thehigh school level. My textbook briefly coversdata files–sequential access–but doesn’t provide many examples of how to write/read multiple variables. Where would

DOS to Windows Conversion

Question: How do I convert a DOS file into a Windows program? Answer: Unfortunately, not very easily. While DOS programs will run under Windows and you may also want to

Resizing Dynamic Array

Question: int num = 50;int **stuff;stuff = new int* [num];for (int i = 0 ; i < num ; ++i) stuff[i] = new int [num]; The code above is copied

Derived Classes

Question: Functions are inherited easily. But if you have a variable in the base class and you want have the same variable but with a different type in the derived

Visual C++ Check/Radio Buttons

Question: How does one go about disabling/enabling buttons and check boxes in dialogs based on the state of other buttons or check boxes? The controls in question are of the

Far pointers in VC 5-6.0

Question: I was trying to do some direct memory stuff (writing to the DOS console buffer or a graphics screen) using my Visual C++ compiler. Unfortunately, the compiler is telling

File Input/Output

Question: I would like to know what is the difference in C between opening a file opened in binary or text mode. Answer: The primary difference is in the handling

Linking in a Resource File

Question: I am creating a Windows app using CC++. I have been using a shareware C compiler and a shareware resource compiler. I have compiled my .rc file into a

Rename a file

Question: In VB, how do you rename a file (at runtime)? Answer: Use the FileSystem object (Microsoft Scripting Runtime, SCRRUN.dll) as follows: Dim fs As New FileSystemObjectDim f As FileSet

Relocating Declarations Can Enhance Performance

On some occasions, the performance boost that can result from moving declarations is quite considerable. Consider this example: void use() { string s1; if (condition == false){ return; //s1 was

Using Piped Streams in an Application

Java’s PipedInputStream and PipedOutputStream classes allow you to write data to an OutputStream object and to read this data from an InputStream object (see the tips “Pass Data Between Threads

Display Tooltips on Your Hyperlinks

Web authors should be used to using the ALT tag to provide a textual label for an image. However, you can’t apply ALT text to a textual link, and most

Prevent Fields From Being Serialized

Objects are made serializable by implementing the java.io.Serializable interface. In general, when you serialize an object instance, all of the instance’s fields are considered to be part of its state,

Perform Safe Downcasts

A downcast is a cast from a base to a derived object. Before the introduction of RTTI to the language, downcasts were regarded as bad programming practice–they were unsafe and

Unroll Loops to Optimize Your Code

A compiler can automatically optimize the code by unrolling loops. Consider this code: int *buff = new int[3]; for (int i =0; i