An Introduction to Programming with C++ Fifth Edition

An Introduction to Programming with C++

Fifth Edition

Chapter 11Arrays

An Introduction to Programming with C++, Fifth Edition 2

Objectives

• Declare and initialize a one-dimensional array

• Manipulate a one-dimensional array

• Explain the bubble sort algorithm

• Pass a one-dimensional array to a function

• Use parallel one-dimensional arrays


Objectives (continued)

• Declare and initialize a two-dimensional array

• Enter data into a two-dimensional array

• Search a two-dimensional array

• Utilize a one-dimensional array in a .NET C++ program


Concept Lesson

• Using Arrays

• One-Dimensional Arrays

• Storing Data in a One-Dimensional Array

• Manipulating One-Dimensional Arrays

• Passing a One-Dimensional Array to a Function


Concept Lesson (continued)

• Using Parallel One-Dimensional Arrays

• Two-Dimensional Arrays

• Storing Data in a Two-Dimensional Array

• Searching a Two-Dimensional Array


Using Arrays

• Simple variable is unrelated to other variables in computer’s internal memory– Also called a scalar variable

• Array is a group of variables– Same name and data type– Variables are related in some way– Most commonly used

• One-dimensional

• Three-dimensional


One-Dimensional Arrays

• Visualize a one-dimensional array as a column of variables– Subscript (or index) identifies each variable

• Indicates the variable’s position in the array

• Subscript of first variable is 0

• Begin by populating the array so it does not contain garbage

Element


One-Dimensional Arrays (continued)


Storing Data in a One-Dimensional Array

• Can use an assignment statement to enter data into an array– See Figure 11-3

• Can use >> and getline()– See Figure 11-4


Storing Data in a One-Dimensional Array (continued)


Manipulating One-Dimensional Arrays

• Common array manipulation functions– Display the contents of an array– Access an array element using its subscript– Search an array– Calculate the average of the data stored in an array– Find the highest value stored in an array– Update the array elements– Sort the array elements using bubble sort


Displaying the Contents of aOne-Dimensional Array

• Function may need simply to display the contents of an array


Displaying the Contents of aOne-Dimensional Array (continued)


Using the Subscript to Access an Element in a One-Dimensional Array

• Before accessing element, verify if subscript is valid


Searching a One-Dimensional Array

• Sales manager wants to determine the number of salespeople selling above a specific amount– Function searches the sales array

• Array contains amount sold by each salesperson

• Look for values greater than the amount provided by sales manager


Searching a One-Dimensional Array (continued)


Calculating the Average Amount Stored in a One-Dimensional Numeric Array

• Prof. Jeremiah wants to calculate and display average test score earned by students on final– Function adds test scores that are stored in array

• Then, divide sum by number of elements


Calculating the Average Amount Stored in a One-Dimensional Numeric

Array (continued)


Determining the Highest Value Stored in a One-Dimensional Array

• Sharon Johnson keeps track of the amount of money she earns each week– Function displays highest amount earned in a week

• Stores pay amounts in a one-dimensional array


Determining the Highest Value Stored in a One-Dimensional Array (continued)


Updating the Values Stored in aOne-Dimensional Array

• Sales manager at Jillian Company wants a function that increases the price of each item company sells– Function stores prices in a one-dimensional array

• Then, increase value stored in each element

• Also, display each item’s new price on screen


Updating the Values Stored in aOne-Dimensional Array (continued)


Sorting the Values Stored in aOne-Dimensional Array

• Arranging data in a specific order is called sorting– Ascending or descending order

• Bubble sort is quick and easy (for small arrays)– Adjacent elements that are out of order are swapped


Sorting the Values Stored in aOne-Dimensional Array (continued)


Passing a One-Dimensional Array to a Function

• By default, scalar variables are passed by value– To pass by reference, use address-of (&) operator

• Arrays in C++ are passed by reference – More efficient – Address of first element is passed to function– Address-of operator is not used


Passing a One-Dimensional Array to a Function (continued)


Using Parallel One-Dimensional Arrays

• Takoda Tapahe wants a program that displays the price of the item whose product ID she enters


Using Parallel One-Dimensional Arrays (continued)

• Parallel arrays are two or more arrays whose elements are related by their position in the arrays– Related by their subscript


Two-Dimensional Arrays

• Two-dimensional array resembles a table– Elements are in rows and columns– Each element is identified by two subscripts

• Subscripts specify the variable’s row and column position in the array


Two-Dimensional Arrays (continued)


Storing Data in a Two-Dimensional Array

• You can use an assignment statement to enter data into a two-dimensional array– Or use >> and getline()

• Use two loops to access every element in a two-dimensional array– One loop tracks row subscript– Other loop tracks column subscript


Storing Data in a Two-Dimensional Array (continued)


Searching a Two-Dimensional Array

• Two one-dimensional (parallel) arrays can be replaced with one two-dimensional array


Searching a Two-Dimensional Array (continued)


Summary

• An array is a group of variables that have the same name and data type and are related in some way– One-dimensional

• Visualize as a column of variables

– Two-dimensional• Visualize as a table

• You must declare an array before you can use it

• Each elements in a one-dimensional array is assigned a subscript– First element has subscript 0


Summary (continued)

• Parallel arrays are two or more arrays whose elements are related by their subscript in the arrays

• To create a two-dimensional array specify the number of rows and columns– Each element is identified by two subscripts

• First subscript represents the element’s row location

• Second subscript represents its column location

• Use two loops to access every element in a two-dimensional array


Application Lesson: Using Arrays in a C++ Program

• Lab 11.1: Stop and Analyze

• Lab 11.2– Program should either display the monthly rainfall

amounts on the screen or calculate and display the total rainfall amount

• Lab 11.3– Modified program will use a value-returning function, calcTotal(), to calculate the total rainfall amount

• Lab 11.4: Desk-Check Lab

• Lab 11.5: Debugging Lab

An Introduction to Programming with C++ Fifth Edition

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