- The document discusses nested selection structures, which involve making multiple decisions using if/else statements. This allows for primary and secondary decisions to be made before executing code. - Nested selection structures are useful when more than one condition must be evaluated to determine the proper course of action. They can be represented through flowcharts and coded in C++ using proper indentation. - Common logic errors in writing nested structures include using compound conditions instead of nesting, reversing the order of decisions, having unnecessary nesting, or including redundant comparisons.

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Introduction to Programming in C++
Eighth Edition
Lesson 6.1:
More on the Selection Structure
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2. • Include anested selection structure in pseudocode andin
aflowchart
• Codeanested selection structure
• Recognizecommon logic errors in selection structures
• Include amultiple-alternative selection structure in
pseudocode and in aflowchart
• Codeamultiple-alternative selection structure in C++
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An Introduction to Programming with C++, Eighth Edition 2
Objectives

3. • True and false paths of aselection structure cancontain
other selection structures
• Inner selection structures are referred to asnested
selectionstructures; contained (nested) within an outer
selection structure
• Nested selection structures are used when morethan
one decision needs to be made before choosing an
instruction
• Inner (nested) selection structures are indentedwithin
their outer selectionstructures
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Nested Selection Structures

4. Figure 6-1 Problem that requires a selection structure
Nested Selection Structures (cont’d.)
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5. Nested Selection Structures (cont’d.)
Figure 6-2 Problem that requires a nested selection structure
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6. Nested Selection Structures (cont’d.)
Figure 6-3 Problem that requires two nested selection structures
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7. • Outer and inner selection structures can be thought of
asmaking primary and secondary decisions,
respectively
• Secondary decision is called such because whether it
needs to be made depends on the result of aprimary
decision
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Flowcharting a Nested Selection
Structure

8. Flowcharting a Nested Selection
Structure (cont’d.)
Figure 6-5 Problem specification for voter eligibility problem
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9. Figure 6-5 A correct solution to the voter eligibility problem
Flowcharting a Nested Selection
Structure (cont’d.)
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10. Figure 6-6 Another correct solution to the voter eligibility problem
Flowcharting a Nested Selection
Structure (cont’d.)
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11. • Codefor nested selection structures usesthe if and
else statements
• Nested selection structures can be placed in either if
or else statement blocks
• Correct tabbing makescode easier to read
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Coding a Nested Selection Structure

12. Coding a Nested Selection Structure
(cont’d.)
Figure 6-7 Code and sample run of the voter eligibility program
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13. • Four common logic errors made when writing selection
structures
– Usingacompound condition rather than anested
selection structure
– Reversingthe outer and nesteddecisions
– Usingan unnecessary nested selection structure
– Including an unnecessary comparison in acondition
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Logic Errors in Selection Structures

14. Logic Errors in Selection Structures
(cont’d.)
Figure 6-8 Problem specification and a correct algorithm for the
Miller’s Car Rental
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15. Figure 6-9 Sample data and expected results for the algorithm
shown in Figure 6-8
Figure 6-10 Result of desk-checking the correct algorithm
Logic Errors in Selection Structures
(cont’d.)
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