IT4201:Rapid Application Development RAD

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IT4201 Rapid Application Development (RAD)

• rad_at_ict.cmb.ac.lk

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Introduction to Visual Basic
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Introduction to Visual Basic

• Microsoft Visual Basic 6 project consists of
  mainly the following
• Forms (will be saved as .frm)
• Modules (.bas)
• Class modules(.cls)
• Designers (.dsr)

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Introduction to Visual Basic

• Visual Basic has Objects
• And Objects have Properties (attributes) and
  Methods
• Object.property value
• e.g. Form1.backcolor rgb(255,0,0)
• Object.method arguments
• form1.show

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Introduction to Visual Basic

• Declaration of Variables
• Dim x as integer
• Implicit and Explicit Declaration
• Scope
• Private,Public
• Static
• Data types

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Introduction to Visual Basic

• Visual Basic 6 has four procedure types
• Sub procedures
• Functions
• Event Procedures
• Property procedures

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Introduction Visual Basic

• Control Structures
• decision structures if then
• if thenelse, select case
• Loop control Do...LoopFor...NextFor Each...Next
  

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Introduction to Visual Basic 6

• Error trapping
• On error Goto ltLine labelgt
• On Error resume next
• On Error Goto 0
• No Global Error trapping
• Err intrinsic object methods and attributes

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Introduction to Visual Basic 6

• ARRAYS
• Arrays allow you to refer to a series of
  variables by the same name and to use a number
  (an index) to tell them apart
• Dynamic, Fixed arrays
• Both have Multi Dimension arrays

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Introduction to Visual Basic 6

• Dim X(10) there are eleven 11 elements
• Option base 1
• Default is zero based
• Ubound () and Lbound()

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Introduction to Visual Basic 6

• One can also give lower bound and upper bound the
  following way
• Dim x(1to10)
• Dim X() ---Dynamic array
• One has to re-declare with
• ReDim statement which is an executable statement

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Introduction to Visual Basic 6

• Preserve statement
• ReDim preserve X(10)
• Erase X initialize the array

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Introduction to Visual Basic 6

• Debugging of an application
• How to place a toggle or Break point

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THANK YOU WISH YOU ALL THE BEST