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.
3. A 10 Minute Delphi for Win32 Quick Start
Create a classic "Hello, World" Windows native code application using Delphi. This tutorial is based on Borland Developer Suite 2006 but you can use any version of Delphi you wish.
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.
In Delphi, you define constants similar to how you define variables but use the Const keyword instead of the Var keyword. Declare global constants in a unit's interface section and unit constants (scope limited to unit) in the implementation section. Declare local constants above the begin..end block.
In coding languages, common End of statement specifiers include a semicolon and return (others exist too). Also of concern when studying a language is can you put two statements on a single code line and can you break a single statement into two or more code lines.
Delphi End of Statement
Object Pascal uses a semicolon ";" as an end of statement specifier and you can put multiple statements on a single line of code and put a single statement on two or more code lines if you wish.
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).
16. Delphi Module
A unit. A unit is defined in its own source file (a .PAS file) that contains types (including classes), constants, variables, and routines (functions and procedures). Each unit begins with unit UnitName; where UnitName must match the filename (minus the .PAS extension). The .PAS unit files are compiled into Delphi Compiled Units with a .DCU extension. A Delphi program is constructed from units. Specifically, the .DCU files are linked into your application. The Delphi compiler is very fast because it only recompiles units that have changed. You can force Delphi to recompile all units with a build all.
Language Overview: Delphi programming language is a type-safe language consisting of hybrid traditional Pascal and OOP features. You code either in a traditional approach using functions, procedures, and global data, or you code using an OOP approach, or a mixture of both.
Target Platforms: Delphi for Win32 is most suitable for creating native code Win32 applications that run on Microsoft Windows.
Object Pascal allows parameters of the same type to be listed together, separated by commas, and followed with a single data type (more params of different data types can follow, after a semi-colon). The default for parameters is by value. For by reference, add var in front of the parameter. Object Pascal also offers constant parameters where you add const in front of the parameter. A constant parameter is like a local constant or read-only parameter the compiler can optimize. You cannot assign a value to a constant parameter, nor can you pass one as a var parameter to another routine.
Rave Reports comes closest to a Delphi standard now but historically there has been no real standard in Delphi development. Do-it-yourself developers sometimes like to use TPrinter for very simple reports. ReportSmith was bundled with the first few versions of Delphi.
Delphi has offered many embedded VCL component report options. Quick Reports has been a part of Delphi since Delphi 2.0 and has been the default report writer for many Delphi developers. Ace Reporter, ReportBuilder and Rave Reports are also very popular. During the time of Kylix, FastReports was popular because of it's cross-platform nature.
Use the + operator to concatenate two strings. Use IntToStr to convert an integer to a string and FloatToStr to convert a floating point number to a string.
An operation with only one operand (a single input). In Object Pascal, a unary operator always precedes its operand (for example, -B), except for ^, which follows its operand (for example, P^). The Delphi unary operators are +, -, and ^ (pointer).
The TYPE operator is also a unary operator and is�evaluated at compile time. The TYPE operator returns the size in bytes of the operand,
Declare global variables in the interface section of a unit, variables declared within the implementation section (but not within a method) have a scope limited to the unit. You declare local variables in a var block outside (above) your begin..end code block. You cannot declare variables in-line (inside begin..end). You can initialize global and unit variables but you cannot initialize local variables. Delphi offers many variable types. Some common variable types include String, WideString, PChar, Integer, Boolean, Single, Double, Pointer, and Variant.
25. Simple Habits Save Lots of Pain
We developers sometimes get "on a roll." We know exactly what we need to do, and the code just flies off our fingertips.
Later, though, we find ourselves in trouble...
New Pascal and Delphi Coding Knowledge Base Post...
Share your knowledge with the WORLD! In addition to adding comments to existing posts, you can post knowledge you've acquired. We welcome full articles (intro with screen shots), general posts (shorter), and tidbits (tips, FAQs, definitions, etc.).
Delphi
Print This
Language Overview: Delphi programming language is a type-safe language consisting of hybrid traditional Pascal and OOP features. You code either in a traditional approach using functions, procedures, and global data, or you code using an OOP approach, or a mixture of both. 
