CIS159 - VB

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CIS159 - VB

• Chapter 1, 2
• Juan Marquezch01.ppt

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Introduction to VB

• Software Development Life Cycle (SDLC)
• VB History (brief)
• Compiling Process
• Categories of Programming Errors
• Complete VB1

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Programming

• Programming is solving a problem using a
  computer.
• A program is a set of specific instructions for a
  computer to follow.
• It is a complex process and each program takes on
  a life of its own called SDLC.
• SDLC Software Development Life Cycle

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SDLC

• Software Development Life Cycle(Program
  Development Cycle)
• There are various methodologies to develop
  programs, but most follow the same process.
• The actual name for each step in the process may
  vary by vendor.

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SDLC 3 Phases, 8 Steps

• Problem Solving Phase
• Problem Definition
• Algorithm Design
• Implementation Phase
• Build, Test, Install, and Train
• Support Phase
• Maintenance
• Obsolete

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SDLC - Problem Solving Phase

• Problem definition (Analysis of the task)Users
  need a form to do a Sales Order Calculation
  (qty, price, tax, freight)
• Algorithm Design (Solution)Design the
  interface.
• Desk check with common and extreme
  data.Programming language not necessarily
  selected yet.

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Problem Solving Diagrams

• Analysis Diagrams / Tools
• Data Flow Diagram (DFD)
• Entity Relationship Diagrams (ERD)
• Functional Descriptions
• Use Case Diagrams (Object-Oriented)

• Design Diagrams / Tools
• Input Output Charts (IPO)
• Flowcharts
• Structure Charts
• Class Diagrams (Object-Oriented)

• Diagrams are independent of programming
  languages.

• We will see some examples of design diagrams
  throughout the course.

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SDLC Implementation Phase

• Implement or Build (Code the program).
• Test the program using test data.Actual output
  must match expected results.
• Deploy or installMay require data conversion or
  hardware upgrades.
• Training User Documentation.

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SDLC Support Phase

• Maintenance change program as needednew tax
  rates, new freight carrier, zip4, Y2K, new area
  code.
• Obsolete program is discarded due to requiring
  too much effort to corrector new technology (DOS
  -gt Windows).

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In Homework Assignments

• You will be provided a
• problem definition
• You will
• Design Algorithm
• Build it
• Test it

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Programming Categories

• Object-Oriented Programming (OOP)
• Emphasis is on identifying objects in a problem
  (student, faculty, etc).
• Objects are then categorized into classes
  (person).
• Classes are used in programs to create and
  manipulate objects.Student As New Person.
• Procedural Programming
• Emphasis is on identifying the procedures or
  steps to solve a problem and then creating a
  program as the solution.
• Event Programming
• Usually related to GUI programming.
• Program reacts to events, such as a user clicking
  on a mouse.
• All of these techniques will be used throughout
  our VB.NET assignments.

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History of VB

• 1960s BASIC introduced by two mathematic
  professors at Dartmouth College as a teaching
  tool.
• BASIC Beginners All-purpose Symbolic
  Instruction Code.
• 1981 IBM Personal Computer introduced
• OS DOS, MS-DOS a line command interface
• MS QuickBasic and QBasic for DOS
• 1988 MS Windows 1.0 released
• 1991 VB 1.0 released
• 1998 VB 6.0 released
• 2002 VB.Net released (as a new language)

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Characteristics of VB

• Visual Basic evolved from BASIC.
• VB is used to developed Windows applications.
• Competitors
• Powerbuilder by Powersoft Corporation
• Delphi by Borland International
• Academic Edition
• Professional Edition

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IDE Software

• VB programs are created in a GUI IDE .
• GUI Graphical User Interface
• IDE Integrated Development Environment
• VB IDE provides the tools and capabilities to
  create very powerful and flexible VB programs.
• Create Forms, Classes, Programs, Database
  connections
• Includes smart editor, compiler, linker, debugger.

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Key Elements of a VB Program

• Design the forms (user interface).
• Design the procedures that will be executed.
• Create forms using various control objects.
• Write procedures that react to object events.

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VB to Machine Language

• VB projects are typed in as text.
• Projects have a .vb extension.
• VB1frm.vb
• Form Resources have a .resx extension.
• VB1frm.resx
• Must be converted to machine language.
• How?
• By compiling

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Compiler and Linker

• Compiler
• Verifies the program is coded with commands it
  recognizes and that the proper syntax was used.
• Creates an object file (machine language).
• Linker
• Combines the programs object file with object
  code of standard routines from the library.
• Creates the final executable file (.exe).
• In the .Net Framework, Common Language Runtime
  (CLR) is the linker.

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Compiling
IDE Editor
vb1.vb
Syntax Errors Warnings
Compiler
Library Objects
Microsoft Intermediate Language (MSIL)
Common Language Runtime (CLR)
vb1.exein memory
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Syntax

• There are several languages to choose from.
• Each language has a set of commands that can be
  used.
• Each language has a set of syntax rules that must
  be followed.
• Syntax determines many things like how commands
  are entered and how each command should end
  (period, semi-colon, etc).

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Three Categories of Errors

• Syntax Errors and Warnings
• Logic Errors
• Run-time Errors
• Actually are logic errors.

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Syntax Errors Warnings

• Detected by compiler.
• Violation of grammar rules.
• Mistyped command.
• Compiler tells you what the error is or what it
  thinks it is.
• Compiler tries to tell you where the error
  occurred.
• Warnings
• Passes syntax rules but not normally coded this
  way.
• Programmer should check for logic error.

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Logic Errors

• Detected and corrected by programmer.
• Program designed or written incorrectly.
• Output generated does NOT match expected output.
• Simple to very complex.
• Using (multiply) instead of (add)
• Test, test, text and verify results.
• This is where programmers earn their money.

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Run-time Errors

• Usually discovered by user, but corrected by
  programmer.
• Program terminates unexpectedly.
• Error access violation
• Usually based on a logic error.
• Divide by zero
• Users do something programmer didnt expect them
  to do.
• Processing unexpected input, such as letters
  instead of numbers.
• Users need to document what they were doing when
  the error occurred to help programmer.

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Summary

• Software Development Life Cycle (SDLC)
• VB History
• Compiling Process
• Categories of Errors
• Next in Class
• Complete VB1