Chapter 4a Relational Operators and Conditional Statements

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Chapter 4a Relational Operators and
Conditional Statements
4a
CI 9008 George Zolla
IS 2020
. Gary Porter
grporter_at_
nps
.navy.mil
Naval Postgraduate School
Monterey, CA
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IfThen

• If weaponsRange lt firingRange Then
• round 1
• fire(round, firingRange, weaponsRange)
• End If
• Does not consider an else condition.
• Useful for simple comparisons

Withing Range?
F
C1 ?
T
Fire
S1 ..
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Decision Structures

• Decision structures in VB are very similar to
  subjunctive statements in English. For instance,
  consider the following subjunctive statement
• If my average golf score is 10 or more strokes
  less than yours, then I will give you a 5 stroke
  handicap on our next game.
• This statement can be directly translated into VB
  code as shown in the following code fragment
• difference yourAverageScore - myAverageScore
• If difference gt 10 Then
• handicap 5
• End If

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IfThenElse

• Handles situations with 2 outcomes
• If condition Then
• statementblock 1
• Else
• statementblock 2
• End If

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Components of IfThenElse statement
l l l l l l l l
End If
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If-Then-Else Blocks

• If weaponsRange lt firingRange Then
• rounds 1
• fire(rounds, weaponsRange, firingRange)
• Else
• speed flankSpeed
• End If

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PseudoCode

• English outline that is easy to translate into
  real code.
• Example
• If users guess random number then
• beep
• else
• display messages
• end if

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Programming Style

• Different If-Then styles are possible.
• Notice how indentation improves the readability
  of the code.
• Keeping the If and End If keywords aligned is a
  common practice that is used to improve code
  readability.