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									Visual Basic Introduction

             IDS 306
  from Shelly, Cashman & Repede
 Microsoft Visual Basic 5: Complete
      Concepts and Techniques
• Parallel Processing -- more than one CPU
  (each with its own memory); able to carry
  out more than one instruction at a time
• Multitasking -- one processor, moves back
  and forth between programs
 Graphical User Interface (GUI)
• Should be under user’s control
  user should be able to customize
• Form should follow function
• Use concepts and metaphors familiar to
  user; parallel real-world experience
• Visually and functionally consistent
• Immediate feedback
• Attempt to prevent user mistakes
Program Development Life Cycle
Methodology -- organized plan that breaks
  process into steps
• Analyze the problem
• Design the problem
• Code the program
• Test and debug program
• Formalize solution
• Maintain the program
     Hierarchical Input Process
       Output (HIPO) Chart
• A.k.a. hierarchy chart or top-down chart
• Represents subdivision of activities visually
• Lowest level instruction -- procedure

                                                  p. I.7
      Flow Chart
•   Process Symbol
•   Input/Output (I/O)
•   Flowline
•   Annotation
•   Decision
•   Terminal
•   Connector
•   Predefined Process
                         p. I.7
 Major Constructs of Structured
• Control Structures
  – Sequence
  – Selection
     • Case
  – Repetition
     • Do…While
     • Do…Until
            Control Structures
• Sequence Control Structure -- used to show a
  single action or one action followed in order
  (sequentially by another)
• Selection Control Structure -- used to tell the
  program which action to take based on a certain
• Case Control Structure -- form of selection
  that allows for more than two alternatives
       Control Structures (cont.)
• Repetition Control Structure -- a.k.a. looping
  or iteration; used when a set of actions is
  performed repeatedly
  – Do...While loop repeats as long as condition is true
    (may never execute)
  – Do...Until loop evaluates condition at end of the
    loop (will always execute at least once)
• Nested Control Structure -- contained within
  other control structures
  Object-Oriented Programming
• Object -- anything real or abstract, about
  which you store both data and operations
  that manipulate the data
• Class -- an implementation that can be used
  to create multiple objects with the same
  attributes and behavior
• Object is and Instance of a Class
       Generalization Hierarchy

                                                 p. I.11
• Object-oriented design tool used to show the
  relationships among classes of objects
        Object-Oriented Terms
• Attribute -- identifying characteristics of
  individual objects, such as name or color
• Operation -- an activity that reads or
  manipulates the data of an object; called
  service in OOD, in OOP called a method
• Message -- has two parts: name of object to
  which message is sent, name of operation that
  will be performed. In OOP called event
          Object Structure Diagram

p. I.12
              Event Diagram

                                            p. I.13

• Used to represent relationships among events and
• Operations shown in rounded rectangles
• Events shown on lines with arrows
     Major Constructs of OOP
• Encapsulation
• Inheritance
• Polymorphism
• Capability of an object to have data
  (properties) and functionality (methods)
  available to the user without the user having
  to understand the implementation within the
• Also called information hiding
• Process of hiding the implementation details
  of an object from its user
• A descendent class (subclass) that differs
  from its superclass in only one way contains
  just the code or data necessary to explain
  the difference
• Also known as subclassing
• Allows an instruction to be given to an
  object in a generalized rather than specific
  detailed command
• Same command will get different but
  predictable results depending on object
  receiving command
• Specific actions, internal to object differ,
  results are the same
Rapid Application Development
• Use of prebuilt objects to make program
  development much faster
• Shorter development life cycles
• Easier maintenance
• Capability to reuse components
              Benefits of OOP
• Reusability -- classes designed to be reused in
  many systems or create modified classes using
• Stability -- classes designed for repeated reuse,
  become stable over time
• Easier Design -- object is a black box
• Faster Design -- can be created from existing
• Process where developers iterate between
  refining the specifications and building
  working models of the system
               Visual Basic
• Properties -- attributes of objects
• Controls -- check boxes, list boxes, etc.
• Forms -- windows that contain application’s
• Events -- messages or requests for service
• Procedures -- operations or services
  – include methods, functions, subroutines
     Creating VB Applications
• Create the interface
• Set the properties
• Write the code

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