Delphi Quick Syntax Reference: A Pocket Guide to the Delphi and Object Pascal Language

By John Kouraklis

The Delphi Quick Syntax Reference is a succinct code and syntax reference guide to Delphi. It presents the fundamental knowledge to get newcomers started with the language and provides a refresher to seasoned or returning Delphi developers.
It covers all the new features added by Embarcadero during the last few years. Delphi celebrates 25 years in 2020 and, alongside the free community version that was introduced a couple of years ago, this syntax guide is a great way to get into the language.
What You Will Learn

• Quickly use and learn Delphi
• Compile, build and run a Delphi program
  
• Master Delphi strings, variables, constants, and operators and how to apply them
• Use conditions, loops, procedures, and functions in Delphi 
• Apply object-oriented programming in Delphi 

Who This Book Is For
Returning or current Delphi developers: The book is a resource for reference for this group of developers especially for the new features that were introduced in the language over the last couple of years. Newcomers to the language: These developers will learn the fundamentals of the language in a very condensed and effective text that accelerates learning. 

• Language: English
• Publisher: Apress
• Release date: Aug 4, 2020
• ISBN: 9781484261125

Book preview

© John Kouraklis 2020

J. KouraklisDelphi Quick Syntax Referencehttps://doi.org/10.1007/978-1-4842-6112-5_1

1. Delphi Pascal

John Kouraklis¹ 

(1)

London, UK

Delphi Pascal or, simply, Delphi is the most popular version of Object Pascal which, in turn, is an extension of the classic Pascal programming language (Cantu, 2016). This chapter introduces the basic concepts of the language.

Delphi As a Programming Language

Delphi is a general-purpose programming language. As a Pascal descendent, it draws its strong typing and syntactical characteristics from the original Pascal language developed by Niklaus Wirth in the early 1970s, but it, loosely, relates to the ISO standard Pascal (i.e., it is not a superset). Over the past decades, Delphi has evolved, and now it has features that makes it a modern programming language capable of building professional software in multiple platforms.

Syntax

If you look at Delphi source code, you will notice that it is dominated by words rather than symbols. Code appears inside a begin...end block rather than inside symbols like curly brackets ({..}) as in other languages.

Typically, code flows from top to bottom and from left to right. This implies that variables, objects, constants, and other elements need first to be declared before they are used (with the exception of forward declaration of classes).

Delphi is case insensitive, meaning that coding elements like variables, objects, methods, and the like can be declared in small or capital letters or in a combination of both. For example, the following declarations are all valid in Delphi: delphiBook, delphi_Book, DelphiBook, DELPHIBOOK, delphiBOOK. There are naming rules which prohibit the use of specific characters (e.g., an identifier cannot start with a number, etc.), but the limitations are very few, and, practically, when you code in Delphi, it is not common to come across them.

A notable difference with other languages is the operator to assign values to variables. In Delphi, a colon followed by the equal sign (:=) is used for this purpose, and the simple equal sign (=) is used to test equality in