1. STRUCTURED CONTROL: BASIC CONTROL OPERATORS
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Structured Programming: Unit 2 Slide 1

2. Objectives
Create a flowchart and pseudocode to describe a conditional program.
Identify situations in which an IFTHENELSE control structure meets the design requirements.
Identify situations in which a CASE control structure meets the design requirements.
Identify situations in which a counter-controlled loop meets the design requirements.
Identify situations in which a trailer-record loop meets the design requirements.
Choose between a DOWHILE and a DOUNTIL control structure.
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Structured Programming: Unit 2 Slide 2

3. IFTHENELSE P? No
Yes d c
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4. Sequential IFTHENELSEP? No
Yes c Q? No
Yes d
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5. Nested IFTHENELSE P? Yes No c Q? Yes No e d
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6. CASE Code? A ProcA B ProcB C ProcC Other ProcOther
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7. Op Code Problem (Flowchart)
Start
Read OP,
N1, N2
OP?
Result= N1+N2
Result= N1+N2
Result= N1+N2
Result= N1+N2
Result= 0
Write
‘Bad input’
Write Result,
N1, N2, Op
Stop
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Structured Programming: Unit 2 Slide 7

8. DOWHILE Loop e Q? 11/29/2018© 2006 ITT Educational Services Inc.
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9. Counter-controlled Loop
Count=x
Count<x
Count>0 No No
Yes
Yes
DoStuff
DoStuff
Count=
Count+1
Count=
Count-1
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Structured Programming: Unit 2 Slide 9

10. Averaging Problem (Flowchart)
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Structured Programming: Unit 2 Slide 10

11. Header Record Logic 11/29/2018© 2006 ITT Educational Services Inc.
Structured Programming: Unit 2 Slide 11

12. Averaging Problem with Header Record
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Structured Programming: Unit 2 Slide 12

13. Averaging Problem with No-Data Test
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Structured Programming: Unit 2 Slide 13

14. Reading a File - Counter DOWHILE Loop
PSEUDOCODE
Count = 0
DOWHILE Count < 3
Read a record
Write a record
Count = Count+1
ENDDO
Count=0
Count =
Count + 1
Count < 3?
Yes
Read a
record
Write a
record No
11/29/2018© 2006 ITT Educational Services Inc.
Structured Programming: Unit 2 Slide 14

15. Reading a File - Header DOWHILE Loop
PSEUDOCODE
Count = 0
DOWHILE Count >0
Read a record
Write a record
Count = Count-1
ENDDO
Count=0
Count =
Count - 1
Count >0
Yes
Read a
record
Write a
record No
11/29/2018© 2006 ITT Educational Services Inc.
Structured Programming: Unit 2 Slide 15

16. Reading a File - Trailer DOWHILE Loop
PSEUDOCODE
Read a record
DOWHILE Code Not 999
Write a record
ENDDO
Read a
record
Code NOT
999?
Yes
Write a
record
Read a
record No
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Structured Programming: Unit 2 Slide 16

17. Reading a File – Auto EOF DOWHILE Loop
PSEUDOCODE
Read a record
DOWHILE Not EOF
Write a record
ENDDO
Read a
record
Not EOF?
Yes
Write a
record
Read a
record No
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18. DOUNTIL Loop Read File DoStuff Yes Done? No
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19. Adding Six Numbers Using DOUNTIL (Flowchart)
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20. Property -- Counter-Controlled (Flowchart)
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21. Property - Header Record Logic (Structure Chart)
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Structured Programming: Unit 2 Slide 21

22. Property -- Header Record Logic -- Overall Control (Flowchart)
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23. DOWHILE vs. DOUNTIL - No Initial Test
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24. DOWHILE vs. DOUNTIL - Initial Test
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25. Summary In this unit, you learned:
How to design a program with conditional logic
IFTHENELSE
Nested IFTHENELSE
Case statements
How to design a program that includes loops
Counter-controlled DOWHILE loop
Trailer record DOWHILE loop
DOUNTIL loop
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Structured Programming: Unit 2 Slide 25