Chapter 11:Arrays

Introduction to Programming with C++

Fourth Edition

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Objectives

• Declare and initialize a one-dimensional array• Manipulate a one-dimensional array• Pass a one-dimensional array to a function• Use parallel one-dimensional arrays• Declare and initialize a two-dimensional array• Enter data into a two-dimensional array

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Using Arrays

• Simple or scalar variable - one that is unrelated to any other variable in memory

• Array - a group of variables that have the same name and data type and are related in some way

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One-Dimensional Arrays

• Each variable in a one-dimensional array is identified by a unique number called a subscript

• The subscript indicates the variable’s position in the array

• First variable in a one-dimensional array is assigned a subscript of 0 (zero), the second a subscript of 1 (one), and so on

• Elements – array variables

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Names of the Variables in a One-Dimensional Array Named prices

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Declaring and Initializing One-Dimensional Arrays

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The letters Array in Memory

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Storing Data in a One-Dimensional Array

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Manipulating One-Dimensional Arrays

• Display the contents of an array• Access an array element using its subscript• Search the array• Calculate the average of the data stored in a

numeric array

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Manipulating One-Dimensional Arrays (continued)

• Find the highest value stored in an array• Update the array elements• Sort the array elements

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Displaying the Contents of a One-Dimensional Array

• displayMonths() function – demonstrates how you can display the contents of the prices array

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displayMonths() Function

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

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Searching a One-Dimensional Array

• Search through an array looking for elements that are greater than a particular value

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Searching a One-Dimensional Array (continued)

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

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Determining the Highest Value Stored in a One-Dimensional Array

• Search through an array looking for an element whose value is larger than the largest value in the array so far (high)

• When the loop is finished, high will be the largest element in the array

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

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Updating the Values Stored in a One-Dimensional Array

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Sorting the Data Stored in a One-Dimensional Array

• Arranging data in a specific order is called sorting

• Bubble sort algorithm: compare adjacent array elements and interchange (swap) the ones that are out of order

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Bubble Sort

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Passing a One-Dimensional Array to a Function

• Arrays are passed by reference– Address of the first element is passed

• Include the name of the array in the function call• Do not include the address-of (&) operator

before the formal parameter’s name in the function header or prototype

• Formal parameter in the header/prototype should list data type, name, and empty square brackets

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

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Using Parallel One-Dimensional Arrays

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

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Using Parallel One-Dimensional Arrays (continued)

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Using Parallel One-Dimensional Arrays (continued)

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Two-Dimensional Arrays

• Two-dimensional array resembles a table• Variables or elements are identified by a unique

combination of two subscripts• Subscripts specify the variable’s row and column

position in the array• Initialize elements by entering a separate

initialValues section, enclosed in braces, for each row in the array

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Two-Dimensional Arrays (continued)

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Two-Dimensional Arrays (continued)

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Two-Dimensional Array in Memory

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Storing Data in a Two-Dimensional Array

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Storing Data in a Two-Dimensional Array (continued)

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Summary

• Array - a group of variables that have the same name and data type

• Subscript – a unique number assigned to each array element in memory

• One-dimensional array - a column of variables• Two-dimensional array - resembles a table in

that it has rows and columns• You must declare all arrays and you should

initialize them

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Summary (continued)

• Various array manipulations:– Displaying the contents of an array– Accessing an array element using its

subscript– Searching an array (“linear search”)– Calculating the average of the data– Finding the highest value stored in an array– Updating the array elements– Sorting the array elements

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Summary (continued)

• Arrays are passed to functions by reference• Parallel arrays are two or more arrays whose

elements are related by their subscript (or position) in the arrays