Delphi

1
Delphi

• Jon Krueger
• Matt Merkel
• Jack Neil

2
Overview

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

3
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.

4
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

5
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

6
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.

7
Delphi concepts

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

8
Delphi Features

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

9
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

10
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

11
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

12
Delphi Example

• A class example

13
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
14
//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
15
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
16
//continuation of last slide begin myText
TStringy.Create(The cat in the hat)
myText.Text There was a cat end end.
17
History of Delphi

• Delphis 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

18
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

19
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, Borlands Delphi was introduced as an
  Object-Oriented version of Turbo Pascal

20
Delphis Market

• Delphis 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

21
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

22
Comparison of Delphi

• Memory management weighs in Delphis 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 Basics main applications include only
  business and database applications

23
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

24
References

• A comparison between Delphi and Visual Basic
• lthttp//www.latiumsoftware.com/en/articles/00010.
  phpgt
• Borland History Why the name "Delphi?"
• lthttp//community.borland.com/article/0,1410,203
  96,00.htmlgt
• Delphi Basics A brief history of Borlands
  Delphi
• lthttp//www.delphibasics.co.uk/Article.asp?Name
  DelphiHistorygt
• Delphi Basics
• lthttp//www.delphibasics.co.ukgt