Delphi Jon Krueger Matt Merkel Jack Neil

Overview Paradigm and problem domains Language concepts Sample code The history of Delphi Language Comparison

Paradigm and problem domains Delphi follows a imperative and OO model The word Imperative come from Latin and means to command. In imperative languages commands update variables. Builds directly on what happens at the hardware level.

Paradigm and problem domains Delphi follows a imperative and OO model You can look at data structures in terms of states. The program is a means to manipulate the states. Variables are used in imperative programming to hold intermediate results of computation. Other major imperative languages include: Fortran, Basic, COBOL, Algol, PL/1, Modula, C, Ada, Perl

Paradigm and problem domains Delphi follows a imperative and OO model Object-Oriented languages are imperative, but considered part of a different paradigm. Delphi is object-oriented Inheritance (single) Polymorphism Encapsulation

Delphi concepts Classes (single inheritance) Interfaces (similar to java) Exception handling Built-in support for Unicode strings and single-byte ANSI strings Very fast compiler and optimizer Compiles to native x86 code.

Delphi concepts Values and types – static, strong, standard primitives (char, real, integer, boolean), enumerated, composite (arrays, records, sets)

Delphi Features Delphi and C++ Builder IDE GUI Builder – drag and drop Source editor Debugger No runtime environment required to execute Delphi object code.

Delphi Structure Program Control Keywords Begin// starts a statement block End// terminates a statement block Exit// exit abruptly from a function or procedure Halt// terminates the program with an optional dialog Try// starts code that has error trapping Uses// declares a list of units (modules) to be imported Var// starts the definition of a section of data variables

Delphi Structure Some routines provided with DELPHI Erase// Erase a file FileSearch// Search for a file in numerous directories FileSetDate// Set the last modified date and time of a file Flush// Flushes buffered text file data to the file Truncate// Truncates a file size TStringList// A class provided with DELHPI that has methods for loading and writing a list of strings from a text file

Delphi Example Reading and writing files var myFile : TextFile; begin AssignFile(myFile, ‘Test.txt’); ReWrite(myFile); //Opens file as new – discards existing contents Append(myFile); //Opens file for appending new data to end Reset(myFile); //Opens a file for read and write access

Delphi Example A class example

Unit Stringy; interface type TString = Class private stText: String; stWordCount: Integer; stFindString : String; stFindPosition : Integer; procedure GetWordCount; procedure SetText(const Value: String); published constructor Create(Text : String); function Replace(from, toStr : String) : Integer; function FindFirst(search : String) : Integer; function FindNext : Integer; property Text : String read stText write SetText; property WordCount : Integer read stWordCount; end;

//continuation of last slide implementation uses SysUtils, StrUtils; constructuror TStringy.Create(Text: String); begin stText:= Text; stFindPosition:= 1; stFindString := ‘’; GetWordCount; end; procedure TStringy.SetText(const Value: String); stText:= Value; stFindPosition := 1; GetWordCount; end; //other methods here

unit Main; uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, Stringy; type TForm1 = class(TForm) procedure FormCreate(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form1: TForm1; procedure TForm1.FormCreate(Sender: TObject); var myText: TStringy; count: integer; position: integer;

//continuation of last slide begin myText := TStringy.Create(‘The cat in the hat’); myText.Text := ‘There was a cat’; end; end.

History of Delphi Delphi’s predecessors date back to as early as 1968 In 1968, a man named Niklaus Wirth began work on a programming language called Pascal, which he completed in 1970 with its first working implementation appearing on a CDC6000 Computer

The Evolution of Pascal In the 1970s, Wirth worked with Jensen on Modula, the next child of Pascal In the very early 1980s, Turbo Pascal was born, and received good press for its excellent compilation and execution speed

Delphi Is Born In the 1990s, a project began at Borland with the Greek Mythological code-name “Delphi” Borland liked the code-name enough to actually use it as the product name 1995, Borland’s Delphi was introduced as an Object-Oriented version of Turbo Pascal

Delphi’s Market Delphi’s main asset was its speed, both in compilation and execution (just like Turbo Pascal) Designed specifically for RAD (Rapid Application Development) Ideal for anything from Business and Database applications to intensive application development

Comparison of Delphi Delphi is most closely related to Visual Basic more than any other programming language Delphi incorporates Object-Orientation but Visual Basic is much more like traditional Basic in the fact that, it is not Object-Oriented

Comparison of Delphi Memory management weighs in Delphi’s favor because the programmer has more freedom in managing objects, such as removing them when they are no longer needed, instead of waiting on a “garbage collector.” Delphi is also broader in the sense of what types of applications it can be used for, whereas Visual Basic’s main applications include only business and database applications

Comparison of Delphi Lower (hardware and time) cost of execution than Visual Basic Visual Basic tends to be easier to learn for someone who is not agile or experienced with programming Visual Basic is more commonly used New programmers are taught Visual Basic

References A comparison between Delphi and Visual Basic Borland History: Why the name "Delphi?" Delphi Basics: A brief history of Borland’s Delphi Delphi Basics