Selection Structures: Single-alternative
Stewart Venit ~ Elizabeth Drake
Addison Wesley
is an imprint of
© 2011 Pearson Addison-Wesley. All rights reserved.
An Introduction to Selection
Structures
• Single-alternative (If-Then)
– A single block of statements to be executed or skipped
• Dual-alternative (If-Then-Else)
– Two blocks of statements, one of which is to be
executed, while the other one is to be skipped
• Multiple-alternative (If-Then-Else-If or
Case/Switch)
– More than two blocks of statements, only one of which
is to be executed and the rest skipped
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Single Alternative: General Form
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Single Alternative
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Single Alternative: Example
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Single Alternative
If something is true Then
Do something (any number
of statements)
End If
Write “How old are you?”
Input Age
If Age >= 18
Set Eligibility = “Yes”
Write “You can vote.”
Do other things…
End If
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Flowchart for Single Alternative Selection
Structures
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Any Questions
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