Clearly Visual Basic: Programming with Visual Basic 2008
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Explore nested selection structures in Visual Basic 2008, including logical operators and algorithms for modified problem specifications. Learn how to apply logical and arithmetic operators effectively.
Clearly Visual Basic: Programming with Visual Basic 2008
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Clearly Visual Basic: Programming with Visual Basic 2008 Chapter 10 Time to Leave the Nest
Objectives • Nest selection structures • Include logical operators in a selection structure’s condition Clearly Visual Basic: Programming with Visual Basic 2008
Nested Selection Structures • Nested selection structure • Selection structure contained (nested) within an outer structure • Figure 10-1 • Shows problem specification and its algorithm • Figure 10-2 • Shows modified problem specification along with modified algorithm • Figure 10-3 • Shows correct algorithm Clearly Visual Basic: Programming with Visual Basic 2008
Putting Rob’s Problem Aside • Figure 10-5 • Shows correct algorithm for problem • Consider how you would change the algorithm • Figure 10-6 • Shows modified problem specification and its algorithm Clearly Visual Basic: Programming with Visual Basic 2008
Download this interface from Dropbox: AddSub Solution If chkSubtraction.Checked = then If intNum1 > = intNum2 then intAnswer = intNum1-intNum2 Else intAnswer = intNum2-intNum1 End If Else intAnswer = intNum1 + intNum2 End If lblAnswer.Text = intAnswer
That’s Way Too Logical for Me • Logical operators (Boolean operators) • Allow you to combine two or more conditions into one compound condition • Always evaluated after any comparison operators in an expression • Arithmetic operators • Evaluated first in an expression Clearly Visual Basic: Programming with Visual Basic 2008
Summary • Both paths in a selection structure: • Can include nested selection structures • Nested selection structures • Used when more than one decision must be made before the appropriate action can be taken • When comparing two numbers: • The first number can be greater than, less than, or equal to the second number Clearly Visual Basic: Programming with Visual Basic 2008
Summary (continued) • Logical operators • Can be included in an If…Then…Else statement’s condition • When the AndAlso logical operator is used to combine conditions: • All conditions must be True for the compound condition to be True • AndAlso operator • Has a higher precedence than the OrElse operator • Arithmetic operators • Evaluated first in an expression Clearly Visual Basic: Programming with Visual Basic 2008
