Pascal and Delphi Coding Most Read KB Posts

Create a classic "Hello, World" Windows native code Console App using Delphi. This tutorial is based on Borland Developer Suite 2006 but you can use any version of Delphi you wish. In this tutorial, you will create a classic "Hello, World!" windows console application. A console application is a type of Windows application that has FULL access to the Win32 API, but it's GUI is limited to a DOS-like text window. When Windows starts a console application, it creates a text-mode console window where the program can display text and the user can interact with the program via the keyboard.

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. 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.

Up until D2005, private and protected were not implemented strictly. Starting with D2005, a traditional strict versions of OOP are supported using the strict keyword. OO purist will want you to use strict private over private and strict protected over protected. I suggest you follow that advice until you both fully understand the differences and have a specific need. Delphi offers a special published specifier which is the same as public members but runtime type information (RTTI) is generated.

This code snippet shows you how to get your NIC MAC address using Borland Delphi.

TStringList Example
Object Pascal doesn't have a native associative array, but you can use a TStringList the same way. (Alternatively, search the Internet for TStringHash and THashedStringList classes for implementations of a true associative array).

Delphi allows you to extend an existing class without using inheritance. Buggy in 2005 and not officially supported but stable and usable in 2006 and above. You declare a class helper similiar to how you declare a class but use the keywords class helper for.

• You can name a helper anything.
• Helpers have access only to public members of the class.
• You cannot create an object instance directly from a class helper.
• self refers to the class being helped.

In Delphi, you use the class keyword followed by the parent class in parens. If you leave out the parent class, your class inherits from TObject.

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.

Note: The following example uses floating point literals. In Delphi, to specify a fractional floating point literal between 1 and -1, you preceed the decimal with a 0; otherwise, you will get a compiler error (i.e. .1 + .1 does not work).

Beginners example of creating and using a class. Early versions of Delphi use the standard OO private, protected, and public visibility specifiers plus add published for RTTI info. Later versions of Delphi add strict private and strict protected for a true OO implementation.

How often have you started a new Delphi project, then spent some time fleshing out the default main form provided by Delphi?

This task only needs to be done once or twice. Delphi then allows us to re-use this work at the start of each new project.

Source code is included.

In this first installment of a New Knowledge Base Series I'll discuss The TForm.OnCloseQuery Event which too frequently goes unhandled.

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. 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.

With the introduction of support for ADO Database access, Borland gave us TADOTable, a quick, easy-to-use component to begin the job of outfitting an existing application with a newer database. But TADOTable is no TTable! It comes with some baggage you can do without.

This primer is intended for those just getting started in Delphi and focuses on displaying things.

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.

In Delphi, you use the class keyword followed by the parent class in parens. If you leave out the parent class, your class inherits from TObject.

Object Pascal

• Operator - Yes. But not Pascal.
• Method - Yes.