Chapter 9 Java Script Control Statements II Outline

Objectives • In this lesson, you will learn: – To be able to use

9. 1 Introduction • Continuation of Chapter 8 – Theory and principles of structured

9. 2 Essentials of Counter-Controlled Repetition • Counter-controlled repetition – – Name of a

Outline While. Counter. html (1 of 2) 2004 Prentice Hall, Inc. All rights reserved.

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9. 3 for Repetition Statement • for repetition statement – Handles all the details

Outline For. Counter. html (1 of 1) 2004 Prentice Hall, Inc. All rights reserved.

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9. 3 for Repetition Statement for keyword Control variable name Final value of control

9. 3 for Repetition Statement Establish initial value of control variable. var counter =

9. 4 Examples Using the for Statement • Summation with for • Compound interest

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9. 5 switch Multiple-Selection Statement • Controlling expression • Case labels • Default case

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9. 5 switch Multiple-Selection Statement case a true case a action(s) break case b

9. 6 do…while Repetition Statement • Similar to the while statement • Tests the

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9. 6 do…while Repetition Structure action(s) condition false Fig. 9. 10 do…while repetition statement

9. 7 break and continue Statements • break – Immediate exit from the structure

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9. 8 Labeled break and continue Statements • Labeled break statement – Break out

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9. 9 Logical Operators • More logical operators – Logical AND ( && )

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9. 10 Summary of Structured Programming • Flowcharts – Reveal the structured nature of

Fig. 9. 20 Single-entry/single-exit sequence, selection and repetition structures. (1 of 3) 2004 Prentice

F F . . . F T break F T switch statement (m ultiple

9. 10 Summary of Structured Programming Fig. 9. 20 Single-entry/single-exit sequence, selection and repetition

9. 10 Summary of Structured Programming 2004 Prentice Hall, Inc. All rights reserved.

9. 10 Summary of Structured Programming Fig. 9. 22 2004 Prentice Hall, Inc. All

9. 10 Summary of Structured Programming Fig. 9. 23 Repeatedly applying rule 2 of

9. 10 Summary of Structured Programming Fig. 9. 24 Applying rule 3 of Fig.

9. 10 Summary of Structured Programming Stacked building blocks Nested building blocks Overlapping building

9. 10 Summary of Structured Programming Fig. 9. 26 Unstructured flowchart. 2004 Prentice Hall,

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Chapter 9 - Java. Script: Control Statements II Outline 9. 1 9. 2 9. 3 9. 4 9. 5 9. 6 9. 7 9. 8 9. 9 9. 10 9. 11 Introduction Essentials of Counter-Controlled Repetition for Repetition Statement Examples Using the for Statement switch Multiple-Selection Statement do…while Repetition Statement break and continue Statements Labeled break and continue Statements Logical Operators Summary of Structured Programming Web Resources 2004 Prentice Hall, Inc. All rights reserved.

Objectives • In this lesson, you will learn: – To be able to use the for and do…while repetition statements to execute statements in a program repeatedly. – To understand multiple selection using the switch selection statement. – To be able to use the break and continue program-control statements. – To be able to use the logical operators. 2004 Prentice Hall, Inc. All rights reserved.

9. 3 for Repetition Statement • for repetition statement – Handles all the details of counter-controlled repetition – for structure header • The first line 2004 Prentice Hall, Inc. All rights reserved.

9. 3 for Repetition Statement for keyword Control variable name Final value of control variable for which the condition is true for ( var counter = 1; counter <= 7; ++counter ) Initial value of control variable Increment of control variable Loop-continuation condition Fig. 9. 3 for statement header components. 2004 Prentice Hall, Inc. All rights reserved.

9. 3 for Repetition Statement Establish initial value of control variable. var counter = 1 counter <= 7 true false Body of loop (this may be many statements) Determine if final value of control variable has been reached. Fig. 9. 4 document. writeln( "<p style="font-size: " + counter + "ex">XHTML font size " + counter + "ex</p>" ); for repetition structure flowchart. 2004 Prentice Hall, Inc. All rights reserved. ++counter Increment the control variable.

9. 5 switch Multiple-Selection Statement case a true case a action(s) break case b action(s) break case z action(s) break false case b true false. . . case z false default action(s) 2004 Prentice Hall, Inc. All rights reserved. true

9. 6 do…while Repetition Statement • Similar to the while statement • Tests the loop continuation condition after the loop body executes • Loop body always executes at least once 2004 Prentice Hall, Inc. All rights reserved.

9. 7 break and continue Statements • break – Immediate exit from the structure – Used to escape early from a loop – Skip the remainder of a switch statement • continue – Skips the remaining statements in the body of the structure – Proceeds with the next iteration of the loop 2004 Prentice Hall, Inc. All rights reserved.

9. 8 Labeled break and continue Statements • Labeled break statement – Break out of a nested set of structures – Immediate exit from that structure and enclosing repetition structures – Execution resumes with first statement after enclosing labeled statement • Labeled continue statement – Skips the remaining statements in structure’s body and enclosing repetition structures – Proceeds with next iteration of enclosing labeled repetition structure – Loop-continuation test evaluates immediately after the continue statement executes 2004 Prentice Hall, Inc. All rights reserved.

9. 10 Summary of Structured Programming • Flowcharts – Reveal the structured nature of programs • Single-entry/single-exit control structures – Only one way to enter and one way to exit each control structure • Control structure stacking – The exit point of one control structure is connected to the entry point of the next control structure 2004 Prentice Hall, Inc. All rights reserved.

Fig. 9. 20 Single-entry/single-exit sequence, selection and repetition structures. (1 of 3) 2004 Prentice Hall, Inc. All rights reserved. F T for statement F T do…while statement F T while statement Rep etition 9. 10 Summary of Structured Programming

F F . . . F T break F T switch statement (m ultiple selection) T break F if statement (single se lec tio n) T Se lectio n if…else statement (d ouble se lec tion) T 9. 10 Summary of Structured Programming Fig. 9. 20 Single-entry/single-exit sequence, selection and repetition structures. (2 of 3) 2004 Prentice Hall, Inc. All rights reserved.

9. 10 Summary of Structured Programming Stacked building blocks Nested building blocks Overlapping building blocks (Illegal in structured programs) Fig. 9. 25 Stacked, nested and overlapped building blocks. 2004 Prentice Hall, Inc. All rights reserved.