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Chapter 5The Selection Structure

• 3 important aspects of programming▫ Sequence (we have experience it)▫ Selection (is that we are going to talk about this next 2 weeks)▫ Repetition

Objectives• Write pseudocode for the selection structure• Create a owchart for the selection structure• Code the if and if/else forms of the selection structure• Write code that uses comparison operators and logical operators• Convert the contents of a char variable to uppercase or lowercase• Convert the contents of a string variable to uppercase or lowercase

Using the Selection Structure• Also called the decision structure

▫ Condition species decision Results in either a true or false answer onl

▫  !hree forms" if # if/else# and switch $or case%

Pseudocode for Selection Structures

Flowcharting the if and if/else Selection Structures

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Coding the if and if/else Selection Structures

selection/repetition symbol

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Selection Statement&switch $or case% statements ne't wee() *o bac( and practice on if/else and owcharts)Comparison +perators

• +ften called relational operators• ,f e'pression has multiple comparison operators at same precedence# it is evaluated from left to

right • Comparison operators are evaluated after any arithmetic operators in the e'pression

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Comparison operators are evaluated after any arithmetic operators in the e'pressionComparison Operator Program 1: Swapping umerical !alues

!!temp is alocal variable

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"ow the program evaluates and run

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Comparison Operator Program #: $ispla%ing the Sum or $i&erence

'ogical Operators• 'ogical operators allow ou to combine two or more conditions into one compound condition

▫ Sometimes called (oolean operators• And/+r operators are evaluated after an arithmetic or comparison operators in an e'pression

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!! use short-circuit evaluation

Using the )ruth )ables•  !o receive a bonus# a salesperson must be rated A and he/she must sell more than -.# in

productrating 00 1A1 22 sales .

•  !o send a letter to all A&rated salespeople and all 4&rated salespeoplerating 00 1A1 55 rating 00 141

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• 6ispla the word 78ass9 if user enters the letter 8 $uppercase or lowercase%• 6ispla 7:ail9 if user enters anthing else

Converting a Character to Uppercase or 'owercase

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Comparing Strings• String comparisons are case&sensitive

▫ 7es9# 7;<S9# and 7;es9 are di=erent• 4efore using a string in a comparison# convert it to uppercase or lowercase

▫ >se transform$%

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transform*+ Function Program: Calculating Sales )a,• Calculate and displa the amount of sales ta' that a customer owes•  !a' rate is 3? of purchase price• ,f purchase is made in *unter Count# ta' rate is 3)@?

Summar%•  !he selection structure $decision structure% is one of the three programming structures

▫ :orms" if# if/else# and switch $or case%▫ Represented b a diamond in a owchart▫ >se the CBB if statement to code both the if and if/else forms

Condition can contain variables# constants# functions# and arithmetic# comparison# orlogical operators

• Character and string comparisons are case sensitive▫ >se toupper$%# tolower$% and transform$%

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