 2001 Prentice Hall, Inc. All rights reserved. 1 Chapter 17 - WMLScript: Control Structures I Outline 17.1 Introduction 17.2 Algorithms 17.3 Pseudocode 17.4 Control Structures 17.5 if Selection Structure 17.6 if/else Selection Structure 17.7 while Repetition Structure 17.8 Formulating Algorithms: Case Study 1 (Counter- Controlled Repetition) 17.9 Formulating Algorithms with Top-Down, Stepwise Refinement: Case Study 2 (Sentinel-Controlled Repetition) Formulating Algorithms with Top-Down, Stepwise Refinement: Case Study 3 (Nested Control Structures) Assignment Operators Increment and Decrement Operators Note on Data Types WMLScript Internet and World Wide Web Resources

 2001 Prentice Hall, Inc. All rights reserved Control Structures Fig. 17.1Flowcharting WMLScript’s sequence structure.

 2001 Prentice Hall, Inc. All rights reserved if Selection Structure Fig. 17.2Flowcharting the single-selection if structure.

 2001 Prentice Hall, Inc. All rights reserved if/else Selection Structure Fig. 17.3Flowcharting the double-selection if/else structure. “Passed”

 2001 Prentice Hall, Inc. All rights reserved while Repetition Structure Fig. 17.4Flowcharting the while repetition structure.

 2001 Prentice Hall, Inc. All rights reserved. Outline 6 1 // Fig. 17.6: mean1.wmls 2 // Class average program 3 4 extern function average() 5 { 6 var total = 0; // clear total 7 var gradeCounter = 1; // prepare to loop 8 var grade; // grade input 9 var gradeValue; // number returned by parseInt method while ( gradeCounter <= 10 ){ // loop 10 times 12 grade = Dialogs.prompt( "Enter integer grade", "" ); gradeValue = Lang.parseInt( grade ); total += gradeValue; gradeCounter; 19 } var average = String.format( "%3.2f", ( total / 10 ) ); WMLBrowser.setVar( "classAve", average ); 24 WMLBrowser.go( "#classAverage" ); 25 } Mean1.wmls Loop 10 times. Prompt for user input. Convert the user input to an integer. Add the value input by the user to the total.Increment the counter. Calculate the average.

 2001 Prentice Hall, Inc. All rights reserved. Outline Click Enter to enter the grades The class average is: $classAve Fig17_7.wml Display the class average.

 2001 Prentice Hall, Inc. All rights reserved. Outline 8

 2001 Prentice Hall, Inc. All rights reserved. Outline 9

 2001 Prentice Hall, Inc. All rights reserved. Outline 10 1 // Fig. 17.9: mean2.wmls 2 // Class average program 3 4 extern function average2() 5 { 6 var total = 0; // clear total 7 var gradeCounter = 0; // prepare to loop 8 var average; 9 10 // prompt for input and read grade from user 11 var grade = Dialogs.prompt( "Enter integer grade," + 12 "(-1) to Quit", "" ); // convert grade from a string to an integer 15 var gradeValue = Lang.parseInt( grade ); while ( gradeValue != (-1) ) { // add gradeValue to total 20 total = total + gradeValue; // increment gradeCounter 23 ++gradeCounter; // prompt for input and read grade from user 26 grade = Dialogs.prompt( "Enter integer grade, " + 27 "(-1) to Quit", "" ); // convert grade from string to integer 30 gradeValue = Lang.parseInt( grade ); 31 } 32 Mean2.wmls Prompt for user input.Convert user input to an integer. Loop until a value of –1 is entered by user. Add grade entered to total.Prompt for user input.

 2001 Prentice Hall, Inc. All rights reserved. Outline // termination phase 34 if ( gradeCounter != 0 ) { 35 average = 36 String.format( "%3.2f", ( total / gradeCounter ) ); 37 } 38 else { 39 average = "No grades were entered"; 40 } WMLBrowser.setVar( "classAve", average ); 43 WMLBrowser.go( "#classAverage" ); 44 } Mean2.wmls Calculate class average.Display an error message if no grades were entered.

 2001 Prentice Hall, Inc. All rights reserved. Outline Click Enter to enter the grades The class average is: $classAve Fig17_10.wml Display the class average.

 2001 Prentice Hall, Inc. All rights reserved. Outline 13

 2001 Prentice Hall, Inc. All rights reserved. Outline 14 1 // Fig : count.wmls 2 // Examination-results program 3 4 extern function passFail() 5 { 6 var passes = 0; // number of passes 7 var failures = 0; // number of failures 8 var student = 1; // student counter 9 10 while ( student 8 ) { 27 WMLBrowser.setVar( "tooMany", "Raise Tuition" ); 28 } WMLBrowser.setVar( "numberPass", passes ); 31 WMLBrowser.setVar( "numberFail", failures ); 32 WMLBrowser.go( "#results" ); 33 } count.wmls Loop 10 times.Prompt for user input. Update value of passes if a 1 was entered.Update the value of failures if anything accept a 1 was entered. Update the counter.

 2001 Prentice Hall, Inc. All rights reserved. Outline Click Run to run script Examination results: 27 Passed: $numberPass 28 Failed: $numberFail 29 $tooMany Fig17_13.wml Display the results.

 2001 Prentice Hall, Inc. All rights reserved. Outline 16

 2001 Prentice Hall, Inc. All rights reserved. Outline 17

 2001 Prentice Hall, Inc. All rights reserved Increment and Decrement Operators

 2001 Prentice Hall, Inc. All rights reserved Increment and Decrement Operators

 2001 Prentice Hall, Inc. All rights reserved. Outline 20 1 // Fig : incrementScript.wmls 2 // Increment example 3 4 extern function increment() 5 { 6 var variable1 = 5; // initial variable 7 var variable2 = 5; // initial variable 8 var post1, post2, post3; // results of increment 9 var pre1, pre2, pre3; // results of decrement post1 = variable1; 13 post2 = variable1++; // increment 14 post3 = variable1; pre1 = variable2; 17 pre2 = ++variable2; // decrement 18 pre3 = variable2; WMLBrowser.setVar( "postResult", post1 ); 21 WMLBrowser.setVar( "postResult2", post2 ); 22 WMLBrowser.setVar( "postResult3", post3 ); 23 WMLBrowser.setVar( "preResult", pre1 ); 24 WMLBrowser.setVar( "preResult2", pre2 ); 25 WMLBrowser.setVar( "preResult3", pre3 ); 26 WMLBrowser.refresh(); 27 } IncrementScript.wm ls To begin, the value of variable1 is 5.To begin, the value of variable2 is 5.Postincrement variable1. Preincrement variable2.

 2001 Prentice Hall, Inc. All rights reserved. Outline Postincrementing: 21 $postResult $postResult2 $postResult3 22 Preincrementing: 23 $preResult $preResult2 $preResult Fig17_17.wml Display the results.

 2001 Prentice Hall, Inc. All rights reserved. Outline 22

 2001 Prentice Hall, Inc. All rights reserved Increment and Decrement Operators