Coder KB: Programming Topic

This will show how to make a "hello world" console application in Visual Studio 2008 with C#. Let VS.Net do the work and create a new console application using the menu. Use Console.WriteLine and Console.ReadLine for simple input and output.

David Intersimone ("David I") of Borland demonstrates the latest versions of the Borland Developer Studio 2006 Product

The .Net framework offers a static method in the string class: String.IsNullOrEmpty.

The .Net framework offers a static method in the string class: String.IsNullOrEmpty.

Can I call a DotNet DLL from my Delphi Win32 application? For example, with Delphi 7 or Delphi 2010?

Delphi supports both static and dynamic arrays.

Length() or SizeOf() will correctly identify an unassigned string variable or an empty string.

Many objects in Delphi have events you can use to trigger code. For example, when you add a form to your project you have access to the form events such as onCreate, onShow, onHide, onDockDrop, etc. In addition, Delphi offers module level events initialization and finalization sections.

Delphi also offers a try...finally where code will execute in the finally section no matter what. It's common to put a try...except inside a try...finally:

In Delphi, you can inline assembler code using the asm keyword.

In Delphi, member events are essentially properties of the type method pointer.

Same as Delphi.

Delphi uses // for a single line comment and both {} and (**) for multiple line comments. Although you can nest different types of multiple line comments, it is recommended that you don't. Commenting code generally has three purposes: to document your code, for psuedo coding prior to coding, and to embed compiler directives. Most languages support both a single line comment and a multiple line comment. Some languages also use comments to give instructions to the compiler or interpreter. A special comment. Delphi compiler directives are in the form of {$DIRECTIVE}. Of interest for comments is using the $IFDEF compiler directive to remark out code.

In Prism, you define constants similar to how you define variables but use the Const keyword instead of the Var keyword. Specifying the type is optional. If you don't specify the type, the compiler chooses the most appropriate type for you.

Declare class constants as part of the class definitions. Declare local constants above the begin..end. Although Prism support inline variables, inline constants are not supported.

Delphi.Net first shipped as a compiler only with Delphi 7. Delphi 8 is a .Net dedicated solution (no Win32) but was not clearly better than VS.Net so more developers moved to VS.Net and bypassed Delphi 8. Delphi for .Net shipped with Delphi 2005, 2006, and 2007 but languished because of a lack of development and VS.Net clearly implemented more .Net CLS features than Delphi for .Net. Delphi Prism (Oxygene) strives to keep pace and in some cases out pace C# and VB.Net using the Object Pascal language.

In Prism, a string can be nil (unassigned), assigned an empty string (""), or assigned a value.  Therefore, to check if a string is empty, you have to check against both nil and (""). Alternatively, you can check the length of the string or use String.IsNullOrEmpty.

The Delphi Prism

Most notable for Delphi developers is the fact that Prism does not offer initialization nor finalization sections.

Notice in the more complete example that the semicolon for the begin..end block after end is not included. That tells the compiler something else is coming (the statement is not finished). Also note the semicolon is missing right before the final "else" statement.

Like all .Net languages, Prism events are a separate type of class member. You define a member event by using the event keyword. Events depend on Delegates to define the signature (the type) of the event they represent and they maintain a list of multiple subscribers - unlike in Delphi for Win32, where each event can only have one handler

Use Windows API GetSystemMetrics with SM_CLEANBOOT parameter to determine how Windows was started.

An example of work I did to display a graphic (+ text) in a single column of a DBGrid based on two tables in a Delphi 2006 Application (not limited to later versions of Delphi)

Embarcadero Technologies and RemObjects Software have announced Delphi Prism, a next generation development suite for .NET and Mono, based on RemObjects Software's Oxygene compiler technology.

Delphi Prism will replace both Delphi for .NET and the existing Oxygene product, allowing the two companies to work together on providing one unified solution for managed development.

Key Points:

• Install Delphi Prism as a plug-in to Visual Studio or run as a standalone development tool.
• Targets .Net and Mono.
• Target .NET applications using the latest Microsoft .NET 3.5 technologies such as WinForms, WPF, Silverlight, ASP.NET, and LINQ'
• Mac OS X and Linux with open source CLR technologies such as Mono and Cocoa#'
• No VCL.Net (this Delphi for .Net feature was dropped).
  
• Build Windows applications first and foremost but also build Mac and Linux applications for added flexibility.
• Integrated managed code database engine targeting Windows, Mac OS X, and Linux.
• Supports all CLS features such as generics, sequences, queries and parallel computing.

Java supports marking a full class as abstract as well as class members. A subclass must either implement the abstract members or you must declare the subclass abstract (which delays the implementation to it's subclass).

Java is case sensitive.

Customary casing:

• Classes - Initial Caps (Pascal Casing)
• Variables - Initial lowecase (Camel case)
• Methods - Initial lowecase (Camel case)

The Java comparison operators are:

• < less than
• <= less than or equal to
• == equal to
• >= greater than or equal to
• > greater than
• != not equal

Languages Focus: Exception Trapping

A common usage of exception handling is to obtain and use resources in a "try-it" block, deal with any exceptions in an "exceptions" block, and release the resources in some kind of "final" block which executes whether or not any exceptions are trapped.

The customary primary source file extension for Java code is ".java" which could contain anywhere from a single class to the entire source code.

Other important files:

• .JAR - Java archive file (compressed code file). Archive that contains multiple Java files and is compressed using .ZIP compression; stores Java classes and metadata and may be digitally signed; runs as a program if the Java Runtime Environment (JRE) is installed on the computer.
• .CLASS - compiled source code which are platform-independent. If a source file has more than one class, each class is compiled into a separate .class file. These .class files can be loaded by any Java Virtual Machine (JVM).

When calling a static method from within the same class, you don't need to specify the class name.

Long a proprietary data store format, Microsoft is opening up the Outlook PST file format with the release of a couple new products.

What is the difference between a partial method and an abstract method?

Prestwood Software is sponsoring the Technology is moving fast. During this free two-hour technical seminar, you'll learn the secrets to getting the most out of RAD Studio 2010 and new Windows technologies.  You'll get a firsthand look at new capabilities that will make you more productive and successful with Delphi--, C++Builder--, Delphi Prism-- and Embarcadero-- RAD Studio 2010.

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You cannot create a Delphi unit with the same name as is already in use. For example, do not create a buttons.pas unit for your application because the VCL already has a Buttons.pas unit. The solution is to rename your unit.

Variables that only contain a reference to the values. Reference data type variables only contain a reference to it's constituent value.  Reference data types include objects and strings.  Assignment of one reference type variable to another copies the reference, thus changes to the values in one variable changes the values in the other.

A collection of regular expressions that validate and parse common user data.

How to enable SSL transactions with the Indy HTTP v9 component.

The online tutorials for these controls use IIS, this post describes the same use with the Cassini web server

Arrays in VB Classic use a 0-based indice. UBound returns -1 if the array has no elements, 0 if it has 1, 1 if it has 2, etc.

In VB Classic, you have to add an empty string to the value being compared in order to get consistent results. For example, add &"" to your string varilable or it's code equivalent &vbNullString. Then compare to an empty string or verify it's length to 0 with Len.

• .BAS = VB source code file.
• .CLS = VB class file (one class per file).

By Reference or Value
For parameters, you can optionally specify ByVal or ByRef. ByRef is the default if you don't specify.

VB.Net is not case sensitive. If you type any other case for commands or variables, VB.Net will change it to the accepted or defined case. For example, if you type messagebox.show it is converted to MessageBox.Show.

VB.Net, like VBClassiccode blocks, are surrounded by statement ending keywords that all use End such as End Class, End Sub, End Function, End If, and End If.

The .Net framework offers a static method in the string class: String.IsNullOrEmpty.

Common source code file extensions include:

• .SLN - Solution File. Contains solution specific information such as links to the projects within this solution.
• .VBPROJ - VB.Net Project File. Contains project specific information.
• .VB -VB.Net source file.
• .Designer.VB -VB.Net form file (a text resource file).

Same as VB classic.

The above usage of Left and Substring are equivalent.

Left is a traditional VB approach popular with developers moving from VB Classic to VB.Net. Substring is considered the .Net way of doing string manipulation.

By Reference or Value
For parameters, you can optionally specify ByVal or ByRef. ByVal is the default if you don't specify which is changed from VB Classic (in VB Classic, ByRef was the default).

New virus targets old versions of Delphi but not the applications developed with Delphi and not the current Delphi versions, just Delphi itself. I detest the jerks that write viruses and other forms of malware.  But this one really gets my goat generally because it was a virus that targeted my favorite best-of-breed development tool and specifically because ZDNet reported the problem in a way that implies it targets applications developed by Delphi. Despite ZDNet's tag line, the virus targets old versions of Delphi (4, 5, 6, and 7) but not the applications developed with Delphi and not the current Delphi versions. I sure hope the way ZDNet chose to report this issue doesn't hurt Embarcadero, the owner of Delphi, because of a virus that attacks pre-Embarcadero versions of Delphi.

Sometimes old news is good news.

If you still need to work with Visual Studio 2005, you may find yourself annoyed by that list of Recent Projects on your Start Page; a list you can't clean up - unless you want to go poking around in the Windows Registry.

The nifty little utility at this link takes care of the problem in a clean, straightforward, easy-to-use way.