1 intro to programming & algorithm design arrays copyright 2003 by janson industries this...

1

Intro to Programming & Algorithm Design

Arrays

Copyright 2003 by Janson Industries

This presentation can be viewed on line in a file named: ch08.IntrotoProg.Arrays.ppt

Assg

Copyright 2014 by Janson Industries2

Objectives Explain

Arrays

Advantages of arrays

How to process arrays

Parallel arrays

Multi-dimensional arrays

Show how to implement arrays in Java


Array A programming data structure that

holds multiple values Think of it as a single row of data

Array values Must all be of the same type

An array of strings, or an array of integers, or an array of…

Can't have an array that has both strings and integers and…

Individual values are referred to by an index (or subscript)

The index begins at 0


Array Arrays are fixed in length

Arrays have a size - the max number of values they can hold

An array is assigned a name

Array values can be: Constant

Fixed values for program use• Discount rates, zip codes

Variable Multiple user or file input values

• Shopping cart items


Array When creating, specify

The type of values it will hold The maximum number of values it will hold A name

To indicate this in pseudocode and flowcharts Specify the value type first Then the name [maximum number of values]

Declare Integer itemCosts[7] Declare String stateAbbrs[4]


Array Can use a variable to define size

Instead of a fixed constant

Especially useful for multiple arrays holding related data Lists of items for sale, descriptions, and prices

If number of items for sale changes, just change arraySize and all arrays changed

Declare Integer arraySize = 4Declare String stateAbbrs[arraySize]


Array String stateAbbrs[4] results in

To refer to a particular value, use the variable name and index number in brackets stateAbbrs[2] = "FL" results inIndex 0 1 2 3

Index 0 1 2 3

FL


Array Let's be clear:

stateAbbrs[2] = "FL" results in data be put into the third position of the array

stateAbbrs[4] = "GA" results in?Index 0 1 2 3

FL

An out of bounds error!


Array Advantages Great for storing lists of data

Instead of defining many variables to hold data use one array

Easy to process array data in a loop Another good reason to use a size variable

As mentioned, can assign data in program or read data from keyboard/file and assign to array

9


Using Arrays A pizza parlor application will accept orders for

delivery Only deliver to certain zip codes Will build an array with valid zip codes of

32246 32224 32250

Will ask user for zip code, read it, and read array to confirm it is valid

10


Using Arrays If the zip code is valid, display the text

Great, we can deliver to you!

If not then, Sorry, we can't deliver to you.

In class assg: Create the pseudo code or flow chart to do this

11


Using Arrays

12

Module main()Declare String zipCode, validZipCode[3]validZipCode[0] = "32246"validZipCode[1] = "32224"validZipCode[2] = "32250"Display "What is your zip code?" Input zipCode

A little harder than you thought?

This initializes the array, displays the prompt and reads the zip


Using Arrays

13

Boolean isZipCodeValid = falseFor ctr = 0 to 2

If zipCode = validZipCode[ctr] Then isZipCodeValid = true

End If End ForIf isZipCodeValid = true Then

Display "Great, we can deliver to you!"Else

Display "Sorry, we can't deliver to you."End If

End Module

Need to keep track if zip is valid or not: isZipCodeValid


Using Arrays - SFC


Using Arrays - SFC

15


Using Arrays in Raptor

16

A Raptor array index starts at 1 String stateAbbrs[4] results in

Also, if you enter a zip code (32246) Raptor assumes it is a number Must engage in some "tom foolery" to get it to work rightIndex 1 2 3 4


Using Arrays Raptor

17

When zipCode read we concatenate an "s" to make it a String and

assign to stringZipCode


Using Arrays Raptor

18

In the validity check, we concatenate an "s" to the value in the array

and compare to stringZipCode


Using Arrays Raptor

19

Notice that the user has no idea about the concatenation and that the data is pure. I.e. we could have put the zip codes in

the array with the "s" but this would have "polluted" the data


Using Arrays Raptor

20


Using Arrays In Java

21

Syntax to create similar to pseudocode new type[size]

new String[3] new int[3]

However, must create an array variable and assign array to it type[] name = new type[size]

String[] zipCodes = new String[3]; int[] qtys = new int[3];


Lets look at this closer:

String[] zipCodes = new String[3] ;


22

Creates a String array of size 3

1

Creates a Sting array variable named

zipCodes

2

Assigns the String array to zipCodes (the String array variable)

3



23

Syntax to create similar to pseudocode new type[size];

new String[3]; new int[3];

However, must create an array variable and assign array to it type[] name = new type[size];

String[] zipCodes = new String[3]; int[] qtys = new int[3];



24

None of the Raptor Tom Foolery needed



25


Why Arrays? Could have done the same

thing with this

Why use the array?

If zipCode ="32246" Then isZipCodeValid = true

Else If zipCode ="32224" Then isZipCodeValid = true Else If zipCode ="32250"

Then isZipCodeValid = true

End If End If End If


Why Arrays? There really wasn't a lot less

code using the array

But what happens if the delivery area expands to 6 zip codes?

Declare String validZipCode[3]validZipCode[0] = "32246"validZipCode[1] = "32224"validZipCode[2] = "32250"

For ctr = 0 to 2 If zipCode = validZipCode[ctr] Then

isZipCodeValid = true End If

End For


Why Arrays? The if logic keeps expanding

With the array: Change the size of the array Add an initialization statement

for each new value Change the for statement

sentinel value

And if instead of hard coding the array size, we had created a variable to hold the size…


Why Arrays? …we never have to change the

for statement or size of array And the for works for any number

of zip codesDeclare Integer arraySize = 6Declare String validZipCode[arraySize]validZipCode[0] = "32246"validZipCode[1] = "32224"validZipCode[2] = "32250"validZipCode[3] = "32252"validZipCode[4] = "32244"validZipCode[5] = "32228"For ctr = 0 to (arraySize -1)


End If End For

Note sentinel value in For


Using Arrays Efficiently Using a For loop is inefficient

Will always loop the number of times of the array size

We want to stop looping as soon as we find a match

So we'll change the loop to a while with a compound condition

30


Using While to Search

31

Module main() Integer arraySize = 6

Integer ctr = 0 String validZipCode[arraySize], zipCode

Boolean isZipCodeValid = false validZipCode[0] = "32246" validZipCode[1] = "32224" validZipCode[2] = "32250" validZipCode[3] = "32252" validZipCode[4] = "32244" validZipCode[5] = "32228"

Display "What is your zip code?" Input zipCode


Using Arrays

32

While (ctr < arraySize AND isZipCodeValid = false)


End If ctr = ctr + 1

End While

If isZipCodeValid = true ThenDisplay "Great, we can deliver to

you!"Else

Display "Sorry, we can't deliver to you."

End Module


Using Arrays SFC

33


Using Arrays SFC

34


Using Arrays Raptor

35


Using Arrays Raptor

36

Notice the argument needed to work in

Raptor


Using Arrays Raptor

37


import java.util.Scanner;

public class ArrayPgmWhile {// Variables and objects needed to read from command line

static Scanner keyboard = new Scanner(System.in);

public static void main(String[] args) {

// Variables and objects needed to hold input, intermediate values, and results

int arraySize = 6;int ctr = 0;String[] validZipCode = new String[arraySize];String zipCode ="";Boolean isZipCodeValid = false;

// Initialize the array with valid zip codesvalidZipCode[0] = "32246";validZipCode[1] = "32224";validZipCode[2] = "32250";

validZipCode[3] = "32252"; validZipCode[4] = "32244"; validZipCode[5] = "32228";

// Prints out a blank line and promptSystem.out.println(" ");System.out.print("What is your zip code? "); 38

Using Arrays Java


// Read the zipzipCode = keyboard.nextLine();

// Check the array while (ctr < arraySize && isZipCodeValid == false) {

if (zipCode.equals(validZipCode[ctr])) {isZipCodeValid = true;

}ctr = ctr + 1;

}

// Tell user whether we can deliver or notSystem.out.println(" ");if (isZipCodeValid) {

System.out.print("Great, we can deliver to you!");}else{

System.out.print("Sorry, we can't deliver to you.");

}// End of method

}// End of class}

39

Using Arrays Java

Notice the argument needed to work in Java


Using Arrays Java

40


Using Arrays The app is so popular, customer now wants it to accept

orders

So if zip code is valid Accept up to 3 order items Store in array Display all items at end

Need New array to hold info Loop to load array Loop to display array contents

41


Using Arrays Better do an external design

(XD) of new app so we can be sure of what the user wants

42

What is your zip code? 33333Sorry, we can't deliver to you.

What is your zip code? 32228

Enter what would you like or Done Pepperoni pizza

Enter what would you like or Done Diet soda

Enter what would you like or Done done

This is what you have ordered:Pepperoni pizzaDiet soda


Validate customer

When array maxed, items

displayed

When "done" entered, items

displayed

Arrays


DisplayItems

Compare To List

Using Arrays Better do an internal design and

modularize

44

main

ValidateCustomer

Get OrderItems

DisplayOrder

ValidateZip Code

Display invalid message

ReadItems

Create Valid List

AskFor Zip


DisplayItems

Compare To List

Using Arrays Define method calls

45

main()

validateCust()

getOrder() showOrder()

ValidateZip Code

Display invalid message

ReadItems

Create Valid List

AskFor Zip


validateCust() needs to return a Boolean value to main indicating if the zip code is valid or not

If valid, main calls getOrder and showOrder

Because getOrder and showOrder use orderArray, make orderArray and orderArraySize static global variables

Global variables are defined within the class but not in a method

Change name of application to OrderEntry

Using Method Calls

46


Because the user is entering data, the array may not have values in every index location Don't want to process empty

locations

Two ways to handle: Check for an empty value Keep track of how many values are

entered Put a sentinel value in the location

after the last valid value

Partially Filled Arrays

47


Pseudocode

48

Main() logic greatly simplified

Declare Integer orderArraySize = 3Declare String orderArray[orderArraySize]

Module main()Declare Boolean isCustValidisCustValid = validateCust()If(isCustValid) Then

getOrder()showOrder()

End IfEnd Module


Pseudocode

49

Alternative way to define and initialize an array

Declare Integer arraySize = 4Declare String stoogesArray[arraySize] = "Moe",

"Larry", "Curly", "Shemp"


Pseudocode

50

Module Boolean validateCust()Integer ctr = 0Boolean isZipCodeValid = false

Integer zipCodeArraySize = 6String validZipCode[zipCodeArraySize] =

"32246", "32224", "32250", "32252", "32244", "32228"

String zipCode



Pseudocode

51

While (ctr < zipCodeArraySize AND isZipCodeValid = false)


End Ifctr = ctr + 1

End While

If isZipCodeValid = false ThenDisplay "Sorry, we can't deliver to

you."End If

return isZipCodeValidEnd Module


Pseudocode

52

Module void getOrder() Integer ctr = 0

String itemDo

Display "Enter what would you like or Done"

Input itemIf item <> "Done" Then orderArray[ctr] = item ctr = ctr + 1End If

While (ctr < orderArraySize AND item <> "Done")End Module

Always want to prompt for an item so a do while is used


Pseudocode

53

Uses a while to show array contents and checks for a blank entry to know when to quit

Module void showOrder() Integer ctr = 0 Display "This is what you have

ordered:" While (ctr < orderArraySize AND orderArray[ctr] <> "")

Display orderArray[ctr] ctr = ctr + 1

End While End Module


SFC - OrderEntry

Global variables defined

main line logic

Copyright 2014 by Janson Industries 55

SFC OrderEntry

main line logic


validateCust()

SFC - OrderEntry


validateCust()

SFCOrderEntry


getOrder()

SFC - OrderEntry


showOrder()

SFCOrderEntry


RaptorOrderEntry

main()

Have to initialize orderArray to nulls ("")


validateCustomer()

RaptorOrderEntry

All the old zip code validation code is here

(don't forget Raptor arrays start at 1 not 0)


RaptorOrderEntryvalidateCustomer()


getOrder()

RaptorOrderEntry


showOrder()

RaptorOrderEntry

Check for null value to see when to stop


When run

RaptorOrderEntry


Alternative way to define and initialize an array Don't specify a size for the array

Instead of explicitly creating an array object, supply values Surrounded with {} Separated by commas

Java

String stoogesArray[] = {"Moe", "Larry", "Curley", "Shemp"};


Have the pseudocode and flowcharts adequately defined what the application should do? I hope you said yes!


public class OrderEntry {// Variables and objects needed to read from command line

static Scanner keyboard = new Scanner(System.in);// Global variables and objects

static int orderArraySize = 3;static String[] orderArray = new String[orderArraySize];

// Checks that zip code is deliverable private static boolean validateCust(){

// Variables and objects needed to hold input and processing statusString zipCode ="";Boolean isZipCodeValid = false;

Java OrderEntry

validateCustomer()


// Variables and objects needed to hold valid zip codesint zipCodeArraySize = 6;

// Create and initialize the array with valid zip codesString[] validZipCode = {"32246", "32224", "32250",

"32252", "32244", "32228"} ;

// Prints out a blank line and user promptSystem.out.println(" ");System.out.print("What is your zip code? ");

// Read the zipzipCode = keyboard.nextLine();

// Check the array to validate the entered zip codeint ctr = 0;while (ctr < zipCodeArraySize && isZipCodeValid == false) { if (zipCode.equals(validZipCode[ctr])) {

isZipCodeValid = true; }

ctr++; }

// Possibly displays invalid messageif (isZipCodeValid == false) {

System.out.print("Sorry, we can't deliver to you.") }

System.out.println(" ");

// Returns whether zip was valid or notreturn isZipCodeValid;

}


// Prompts user for order items and stores in orderArrayprivate static void getOrder(){

// Variables and objects needed to store order itemsString item = "";

// Prompt for and read order items then store in an array.int ctr = 0;do { System.out.print("Enter what would you like or Done

"); item = keyboard.nextLine(); if (!item.equalsIgnoreCase("Done")) {

orderArray[ctr] = item;ctr++;

} System.out.println(" ");} while (ctr < orderArraySize

&& !item.equalsIgnoreCase("Done"));}

Java OrderEntrygetOrder()

Notice use of equalsIgnoreCase()


// Displays ordered itemsprivate static void showOrder(){

int ctr = 0; System.out.println("This is what you have ordered:");

while (ctr < orderArraySize && !(orderArray[ctr] == null) ){

System.out.println(orderArray[ctr]);ctr++;

}}

public static void main(String[] args) {// Variable to hold customer status

Boolean isCustValid = false;isCustValid = OrderEntry.validateCust();if (isCustValid){

OrderEntry.getOrder();OrderEntry.showOrder();

}// End of method

}//End of class}

Vastly simplified main()

Java OrderEntryshowOrder()


showOrder()

Java OrderEntry


Passing Arrays Just like strings and numbers, arrays can be passed and returned from methods

Syntax pretty much the same

To pass a string array methodName(arrayVariableName)

To return a string array in header: String[] methodName at method end: return arrayVariableName

Arrays make passing many or a variable number of values easier


Passing Arrays Instead of making orderArray a global variable, have

getOrder create orderArray & return it showOrder will have orderArray passed to it

Must change Both methods headers getOrder needs a return statement main creates an array variable, assigns orderArray (returned by getOrder) to it, passes it to showOrder


Passing Arrays Pseudocode

75

Declare Integer orderArraySize = 3

Module main() Declare String orderArray[orderArraySize] Declare Boolean isCustValid isCustValid = validateCust() If(isCustValid) Then

orderArray[] = getOrder()showOrder(orderArray[] )

End IfEnd Module

orderArray not a global variable

Main creates variable, assigns the array returned by getOrder to it, passes it to showOrder


No Changes to validateCust

76



"32246", "32224", "32250", "32252", "32244", "32228"

String zipCode




77


if zipCode = validZipCode[ctr] then isZipCodeValid = true

End Ifctr = ctr + 1

End While

if isZipCodeValid = false thenDisplay "Sorry, we can't deliver to

you."End If




78

Module String[] getOrder() Integer ctr = 0

String item, orderArray[orderArraySize]Do

Display "Enter what would you like or Done"Input itemIf item <> "Done" Then orderArray[ctr] = item ctr = ctr + 1End If

While (ctr < orderArraySize AND item <> "Done")Return orderArray

End Module

Change method header to return array, create and return orderArray



79

Change header to accept orderArray

Module void showOrder(String orderArray[]) Integer ctr = 0

Display "This is what you have ordered:" While (ctr < orderArraySize AND orderArray[ctr] <> "")

Display orderArray[ctr] ctr = ctr + 1



private static String[] getOrder(){

//Variables and objects needed to store order itemsString item = "";String[] orderArray = new

String[orderArraySize];

//Variables and objects needed to read from command line : : :

Same code as before : : :

return orderArray;//End of method}

public class OrderEntryPassArray {

//Global variables and objectsstatic int orderArraySize = 3;

private static boolean validateCust(){ : : :

Same code as before : : :

orderArray no longer a global

variable

A String array will be

returned

orderArray is a local

variable

orderArray is returned

Passing Arrays Java


private static void showOrder(String[] orderArray) {int ctr = 0;

// Displays order itemsSystem.out.println("This is what you have ordered:");

while (ctr < orderArraySize && !(orderArray[ctr] == null)) {

System.out.println(orderArray[ctr]);ctr++;

}// End of method}public static void main(String[] args) {

//Variables to hold customer status and ordersBoolean isCustValid = false;String[] orderArray;

isCustValid = OrderEntryPassArray.validateCust();if (isCustValid){

//If valid invokes getOrder and receives orderArrayorderArray = OrderEntryPassArray.getOrder();

//Invokes showOrder and passes orderArray to the methodOrderEntryPassArray.showOrder(orderArray);

}//End of method}

showOrder accepts a String

array

main has a local String array

variable

main gets the order array and passes it to showOrder


Still works correctly


Processing An Array How can you find the following

for the values in an array Largest

Smallest

Total

Average


Processing An Array Say you have an array of test

scores Create a variable to hold the

largest value

Read the first value and set it as the largest

Then loop through the remaining values and compare each to the largest

If new value larger, set largest value to it


Processing An Array

Declare Integer largestValue, ctr = 1largestValue = testScoresArray[0]While (ctr < testScoresArraySize AND testScoresArray[ctr] <> "") If testScoresArray[ctr] > largestValue Then

largestValue = testScoresArray[ctr] End If

ctr = ctr + 1End While

Finding the largest value


Processing An Array

Declare Integer smallestValue, ctr = 1smallestValue = testScoresArray[0]While (ctr < testScoresArraySize AND testScoresArray[ctr] <> "") If testScoresArray[ctr] < smallestValue Then

smallestValue = testScoresArray[ctr] End If

ctr = ctr + 1End While

Finding the smallest value Very similar to largest search


Finding the sum

87

Processing An Array

Declare Integer sumValue, ctr = 0While (ctr < testScoresArraySize AND testScoresArray[ctr] <> "") sumValue = sumValue + testScoresArray[ctr] ctr = ctr + 1End While


Finding the average Have to find the sum then divide by the number of values

Which we have kept track of with ctr

88

Processing An Array

Declare Integer sumValue, avgValue, ctr = 0While (ctr < testScoresArraySize AND testScoresArray[ctr] <> "") sumValue = sumValue + testScoresArray[ctr] ctr = ctr + 1End WhileavgValue = sumValue/ctr


Will have main() perform all the calculations

Will have two other methods initializeScoreTestArray()

Loads the scores

displayValues() shows the scores and calculated values

89

Processing An Array - Raptor


Processing An Array - RaptorinitializeTestScoreArray()


Processing An Array - RaptordisplayValues()

Loop to show individual scores


Processing An Array - RaptordisplayValues()

Puts out a blank line then the four calculated values


Processing An Array - Raptormain()

Initialize the scoresSet ctr to the 2nd

test score because…… we capture the first test score with

these variables

Loop from 2 until ctr = 6

Calc the sum


Processing An Array - Raptormain()

Checks the array for smaller and larger

values

Calcs average and calls display module (notice

ctr-1 in avg calc)


Processing An Array - Raptor

Results


Parallel Arrays Use more than one array to store

many pieces of related information

Related info stored in same relative position in each array

For instance storing employee information like Name Address Phone number


Parallel Arrays For 3 employees with the

following info:

Joe lives at 1 Main St. and has a phone number of 111-1111

Mary lives at 2 Oak St. and has a phone number of 222-2222

Pam lives at 1 Elm St. and has a phone number of 333-3333


Parallel Arrays Done with the following 3 arrays

Name array

Address array

Phone array

Joe

1 MainSt.

111-1111

Mary

2 OakSt.

222-2222

333-3333

3 ElmSt.

Pam


Parallel Arrays Change OrderEntry to accept a

quantity for each item User will enter a qty for each order item

Qty will be saved in qtyArray

Accumulate total number of items

Change message to say The following are the XX items you have

ordered Have the qty before each item If qty > 1, add an "s" to item (make item

plural)


Parallel Arrays So when an item is entered

It's qty is entered in the same position in the qtyArray

pizza

6


Parallel Arrays Because getOrder creates two

arrays must make the array variables global

Why? Java methods can only return a

single variable No way to return 2 array variables


Parallel Arrays getOrder will

Display the new text

Populate both arrays with values

Calculate and return the total number of items

main will get the total and pass to showOrder

showOrder will receive the total and display the new text


Parallel Arrays Here’s the external design of

changes to application

103

What is your zip code? 33333Sorry, we can't deliver to you.

What is your zip code? 32228

Enter what would you like or Done Pepperoni pizzaHow many Pepperoni pizzas would you like 6

Enter what would you like or Done Small diet colaHow many Small diet colas would you like 1

Enter what would you like or Done Large calzoneHow many Large calzones would you like 5

The following are the 12 items you have ordered:6 Pepperoni pizzas1 Small diet cola5 Large calzones

Notice "s" on items with qty >1



104

Declare Integer orderArraySize = 3Declare String orderArray[orderArraySize]Declare String qtyArray[orderArraySize]

Module main() Declare Boolean isCustValid Integer total isCustValid = validateCust() If(isCustValid) Then

total = getOrder()showOrder(total)

End IfEnd Module

orderArray & qtyArray are

global parallel arrays

New variable total passed



105



"32246", "32224", "32250", "32252", "32244", "32228"

String zipCode




106


if zipCode = validZipCode[ctr] then isZipCodeValid = true

End Ifctr = ctr + 1

End While

if isZipCodeValid = false thenDisplay "Sorry, we can't deliver to

you."End If




107

Module String[] getOrder() Integer ctr = 0, totalQty

String item, qtyDo

Display "Enter what would you like or Done"Input itemIf item <> "Done" Then orderArray[ctr] = item

Display “How many “, item, “s would you like“

Input qtyqtyArray[ctr] = qtytotalQty = totalQty + qty

ctr = ctr + 1End If

While (ctr < orderArraySize AND item <> "Done")Return totalQty

End Module

New variables to hold qty info

Setting parallel

arrays' values



108

Module void showOrder(Integer totalQty) Integer ctr = 0 Display “The following are the “, totalQty,

“ items you have ordered” While (ctr < orderArraySize AND orderArray[ctr] <> "")

Display qtyArray[ctr], " ", orderArray[ctr] If (qtyArray[ctr] > 1)

Display “s” End If ctr = ctr + 1


Displaying item and qty

info

Make item plural


Passing Arrays Raptor

109

Just declared some new variables

No changes to validateCustom

er



110

Declare the new qty variables

Initialize totalQty


Get qty info, load into array

Calc totalQty



112

New msg variable needed to pluralize

item

Make msg plural

Build msg with qty and item

Display total items


private static int getOrder(){//Variables and objects needed to store order items

String item = "";String qty = "";int totalQty = 0;

//Variables and objects needed to read from command line : : :

if (!item.equalsIgnoreCase("Done")) {orderArray[ctr] = item;System.out.print("How many " + item +"s would you like ");try {

qty = dataIn.readLine();qtyArray[ctr] = qty;totalQty = totalQty + Integer.parseInt(qty);

} catch (IOException e) {e.printStackTrace();

}ctr++;

} : : :

return totalQty;

113

public class ParallelArrays {//Global variables and objects

static int orderArraySize = 3;static String[] orderArray = new String[orderArraySize];static String[] qtyArray = new String[orderArraySize]; : : :

New qtyArray and global variable

New qty and totalQty variables

Get qty only if not

done

Load qtyArray and accumulate

totalQty

Return totalQty


114

private static void showOrder(int totalQty){ int ctr = 0; //Displays order items System.out.println("The following are the " + totalQty + " items you have ordered"); while (ctr < orderArraySize && !(orderArray[ctr] == null)){ System.out.print(qtyArray[ctr] + " "); System.out.print(orderArray[ctr]); if (Integer.parseInt(qtyArray[ctr]) > 1) { System.out.println("s");} else {System.out.println(" ");}

ctr++; }//End of method}

public static void main(String[] args) {// Variable to hold customer status

Boolean isCustValid = false;int totalQty = 0;

isCustValid = ParallelArrays.validateCust();if (isCustValid){

totalQty = ParallelArrays.getOrder();ParallelArrays.showOrder(totalQty);

}// End of method

showOrder accepts totalQty

main has a totalQty variable

Gets totalQty and passes

New message

with totalQtyPrints qty and

itemIf more than one, adds an

"s"


Notice the total

and individual amounts

Prompts for items & amounts


Parallel Arrays - Finding a Range Store the upper or lower limit of

each range in the array

Compare value to limit

If < or > (depending on whether upper of lower limit) you have found the correct range

Example assigning a letter grade to a numeric grade 99 entered, A returned


Finding a Range Our ranges for the letter

grades will be F < 64.5

D < 69.5

C < 79.5

B < 89.5

A < 100.5


Parallel Arrays Will create two parallel arrays to

hold the grades and limits

gradeArray

rangeArray

ABC

100.589.579.5

DF

64.5 69.5


Finding a Range When user enters a numeric

grade will compare it to the first value in the rangeArray[] If entered grade less than 64.5 we

have found the correct position in the array

Display the letter grade in the same location of the gradeArray

Else compare to next location in rangeArray, etc.


Finding a Range

120

Module main()Integer arraySize = 5

String gradeArray[arraySize]Real rangeArray[arraySize]

gradeArray[0] = "F"gradeArray[1] = "D"gradeArray[2] = "C"gradeArray[3] = "B"gradeArray[4] = "A"

rangeArray[0] = 64.5rangeArray[1] = 69.5rangeArray[2] = 79.5rangeArray[3] = 89.5rangeArray[4] = 100.5


Integer ctr = 0Integer numericGrade = 0Boolean isGradeAssigned = false

Display " "Display "What is the numeric grade? "Input numericGrade

While (ctr < arraySize AND isGradeAssigned = false) If (numericGrade < rangeArray[ctr]) then

isGradeAssigned = true Else

ctr = ctr + 1; End IfEnd WhileDisplay " "Display "A numeric grade of ", numericGrade,

" is equal to a letter grade of ", gradeArray[ctr]);End Module

Finding a Range


Finding a Range Raptor

122

Initialize the arrays


Finding a Range Raptor

123

Notice how loop condition changed

Initialize the other variables


Finding a Range - Raptor

124


125


public class LetterGrade {// Variables and objects needed to read from command linestatic Scanner keyboard = new Scanner(System.in);

public static void main(String[] args) {// Variable to hold array sizesint arraySize = 5;

// Arrays to hold grade and rangesString[] gradeArray = new String[arraySize];double[] rangeArray = new double[arraySize];

// Initialize the array with letter gradesgradeArray[0] = "F";gradeArray[1] = "D";gradeArray[2] = "C";gradeArray[3] = "B";gradeArray[4] = "A";

// Initialize the array with grade range upper limitrangeArray[0] = 64.5;rangeArray[1] = 69.5;rangeArray[2] = 79.5;rangeArray[3] = 89.5;rangeArray[4] = 100.5;

Java Range Search


126

// Loop control variablesint ctr = 0;Boolean isGradeAssigned = false;

// Variable to hold input valuesdouble numericGradeDouble = 0;

// Prints out a blank line and instructionSystem.out.println(" ");System.out.print("What is the numeric grade? ");

// Read the numeric gradenumericGradeDouble = keyboard.nextDouble();

// Search the array to find the correct rangewhile (ctr < arraySize && isGradeAssigned == false) {

if (numericGradeDouble < rangeArray[ctr]) {isGradeAssigned = true;

} else {ctr++;

}}System.out.println(" ");System.out.print("A numeric grade of " +

numericGradeString+ " is equal to a letter grade of " +

gradeArray[ctr]);// End of method

}// End of class

}

If range found, no need to increase loop

counter


Multidimensional Arrays Arrays don't have to consist of a single row

A multi-row index is a two dimensional array. Examples: A spreadsheet table

An egg carton

Pill box


Multidimensional Arrays Not limited to 2 dimensions

Created same as 1 D arrays, just there are many sizes Number of rows, cols, flats, etc.

3D 6D


Pseudocode

Results in an array with 2 rows and 6 columns

And these are their indices

130

Multidimensional Arrays

Declare String eggCartonArray[2] [6]

[0] [0] [0] [1] [0] [2] [0] [3] [0] [4] [0] [5]

[1] [0] [1] [1] [1] [2] [1] [3] [1] [4] [1] [5]


If data loaded without specifying the index Info loaded one line at a time

From left to right

So

Results in…

131


Declare String eggCartonArray[2] [6] = "a", "b", "c", "d", "e", "f", "g", "h", "i', "j", "k", "l"


132


a b c d e f

g h i j k l

Declare String eggCartonArray[2] [6] = "a", "b", "c", "d", "e", "f", "g", "h", "i', "j", "k", "l"


9 x 3, 2D array holds the par values for a 9 hole golf course

User enters their score for each of the holes, which goes into col 2

Program calculates Over/under for each hole (col 3)

Whether it is a birdie, eagle, par, bogie, double bogie, ugh.

Total for the round

133



Multidimensional Arrays - XDWhat was your score on hole 1? 3What was your score on hole 2? 4What was your score on hole 3? 3What was your score on hole 4? 7What was your score on hole 5? 3What was your score on hole 6? 3What was your score on hole 7? 5What was your score on hole 8? 6What was your score on hole 9? 1

You shot a 35 with 2 eagles, 1 birdie, 3 pars, 2 double bogies, 1 ugh



135

Module main()Integer courseSize = 9

Integer scoresArray[courseSize] [3]String namesArray[6], msg = " "Integer namesValuesArray[6] [2]

scoresArray [0] [0] = 3scoresArray [1] [0] = 5scoresArray [2] [0] = 3scoresArray [3] [0] = 3scoresArray [4] [0] = 5scoresArray [5] [0] = 3scoresArray [6] [0] = 3scoresArray [7] [0] = 4scoresArray [8] [0] = 3



136

namesArray[0] = "eagle"namesArray[1] = "birdie"namesArray[2] = "par"namesArray[3] = "bogie"namesArray[4] = "double bogie"namesArray[5] = "ugh"

namesValuesArray[0] [0] = -2namesValuesArray[1] [0] = -1namesValuesArray[2] [0] = 0namesValuesArray[3] [0] = 1namesValuesArray[4] [0] = 2namesValuesArray[5] [0] = 3


Integer ctr = 1, innerCtr = 0, score, totalScore = 0

//Get scores, calc over/under and totalScore For ctr = 1 to 9 Display "What was your score on hole " + ctr + "? " Input score totalScore = totalScore + score scoresArray [ctr - 1] [1] = score scoresArray [ctr - 1] [2] = score - scoresArray [ctr - 1] [0]

//Set ughs and if ugh, don't want to check for other values If (scoresArray [ctr - 1] [2] > 3) Then

namesValuesArray[5] [1] = namesValuesArray[5] [1] +1

innerCtr = 7 End If



//Set birdies, bogies, etc.While innerCtr < 6

If (scoresArray [ctr - 1] [2] = namesValuesArray[innerCtr] [0]) Then

namesValuesArray[innerCtr] [1] = namesValuesArray[innerCtr] [1] + 1

innerCtr = 7 End If innerCtr = innerCtr + 1End While

End For



//Build birdies, bogies, etc. portion of msg For ctr = 0 to 5

If (namesValuesArray[ctr] [1] > 0) Then msg = msg, namesValuesArray[ctr] [1], " ",

namesArray[0] If (namesValuesArray[ctr] [1] > 1) Then

msg = msg, "s, " Else

msg = msg, ", " End IfEnd If

End For

Display "You shot a ", totalScore, " with", msgEnd Module




public class GolfScore {

static Scanner keyboard = new Scanner(System.in);

public static void main(String[] args) {// Variable to hold array sizesint courseSize = 9;

// Arrays to hold dataint scoresArray[][] = new int[courseSize][3];String namesArray[] = new String[6];int namesValuesArray[][] = new int[6][2];

// Various variablesint ctr, innerCtr, score, totalScore = 0;String msg = " ";

// Initialize arrays// Hole par valuesscoresArray[0][0] = 3;scoresArray[1][0] = 5;scoresArray[2][0] = 3;scoresArray[3][0] = 3;scoresArray[4][0] = 5;scoresArray[5][0] = 3;scoresArray[6][0] = 3;scoresArray[7][0] = 4;scoresArray[8][0] = 3; 140

Multidimensional Arrays - Java

Setting the par values

Parallel arrays


Multidimensional Arrays - JavanamesArray[0] = "eagle";namesArray[1] = "birdie";namesArray[2] = "par";namesArray[3] = "bogie";namesArray[4] = "double bogie";namesArray[5] = "ugh";

namesValuesArray[0][0] = -2;namesValuesArray[1][0] = -1;namesValuesArray[2][0] = 0;namesValuesArray[3][0] = 1;namesValuesArray[4][0] = 2;namesValuesArray[5][0] = 3;

//Get scores, calc over/under and totalScorefor (ctr = 1; ctr <= 9; ctr++) { System.out.print("What was your score on hole " + ctr + "? "); score = keyboard.nextInt(); totalScore = totalScore + score; scoresArray[ctr - 1][1] = score; innerCtr = 0;

//Set ughs value if (scoresArray[ctr - 1][2] > 3) {

namesValuesArray[5][1] = namesValuesArray[5][1] + 1;innerCtr = 7;

}


Parallel arrays values


Multidimensional Arrays - Java //Set birdies, bogies, etc. values while (innerCtr < 6) {

if (scoresArray[ctr - 1][2] == namesValuesArray[innerCtr][0]) {

namesValuesArray[innerCtr][1] = namesValuesArray[innerCtr][1] + 1;

innerCtr = 7;}innerCtr = innerCtr + 1;

}}

//Build birdies, bogies, etc. portion of msgfor (ctr = 0; ctr < 6; ctr++) { if (namesValuesArray[ctr][1] > 0) { msg = msg + namesValuesArray[ctr][1] + " " +

namesArray[ctr];if (namesValuesArray[ctr][1] > 1) { msg = msg + "s, ";} else { msg = msg + ", ";}

}}

// Take off the last comma and spacemsg = msg.substring(0, msg.length() - 2);System.out.println(" You shot a " + totalScore + " with" + msg);}

}


Trim off ", "


Points to Remember Arrays contain a series of values

All values must be the same type Array assigned to a variable Each value identified by the

variable name followed by a subscript (ex. priceArray[2])

Search an array: Initialize the subscript to 0 Use a loop to test each array

element value Stop loop when a match is found


Points to Remember Parallel arrays - multiple arrays

where

Each element in one array is associated with the element at the same relative location in another array

Multi-dimensional arrays

Arrays of arrays

Good for holding many sets of related data


Assignments Non-Graded

Chap 8 labs 8.1-8.4

Graded

Chap 8 lab 8.5

145

1 intro to programming & algorithm design arrays copyright 2003 by janson industries this...

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