3 Using Two-Dimensional Arrays Recall that an array is a group of related variables that have the same data type You can visualize a one-dimensional array as a column of variables in memory You can visualize a two-dimensional array as a table in that the variables are in rows and columns You can determine the number of variables in a two-dimensional array by multiplying the number of rows by the number of columns
An Introduction to Programming with C++ Sixth Edition Chapter 12
Two-Dimensional Arrays Objectives Declare and initialize a
two-dimensional array Enter data into a two-dimensional array
Display the contents of a two-dimensional array Sum the values in a
two-dimensional array Search a two-dimensional array Pass a
two-dimensional array to a function An Introduction to Programming
with C++, Sixth Edition2 3 Using Two-Dimensional Arrays Recall that
an array is a group of related variables that have the same data
type You can visualize a one-dimensional array as a column of
variables in memory You can visualize a two-dimensional array as a
table in that the variables are in rows and columns You can
determine the number of variables in a two-dimensional array by
multiplying the number of rows by the number of columns An
Introduction to Programming with C++, Sixth Edition4 Using
Two-Dimensional Arrays (contd.) Each variable in a two-dimensional
array is identified by a unique combination of two subscripts
specifying the variables row and column position Variables located
in the first, second, etc. row of a two-dimensional array are
assigned a row subscript of 0, 1, etc. Similarly, variables located
in the first, second, etc. column of a two-dimensional array are
assigned a column subscript of 0, 1, etc. Using Two-Dimensional
Arrays (contd.) You refer to each variable in a two-dimensional
array by the arrays name immediately followed by the variables row
and column subscripts (in that order), each enclosed in its own set
of square brackets As with one-dimensional arrays, the last row and
column subscripts of a two-dimensional array will always be one
less than the number of rows and columns (respectively) in the
array, since the subscripts begin at 0 An Introduction to
Programming with C++, Sixth Edition5 6 Figure 12-1 Names of some of
the variables in the two-dimensional orders array An Introduction
to Programming with C++, Sixth Edition7 Figure 12-2 Problem
specification for the Caldwell Companys orders program Using
Two-Dimensional Arrays (contd.) An Introduction to Programming with
C++, Sixth Edition8 Figure 12-2 IPO chart for the Caldwell Companys
orders program Declaring and Initializing a Two- Dimensional Array
You must declare a two-dimensional array before you use it As with
one-dimensional arrays, it is good practice to initialize the array
variables Syntax for declaring a two-dimensional array: dataType
arrayName [numberOfRows] [numberOfColumns] = {{initialValues},
{initialValues }, {initialValues }}; dataType specifies the data
type of elements in the array (all elements must have same data
type) numberOfRows and numberOfColumns specify number of rows and
columns in array, respectively An Introduction to Programming with
C++, Sixth Edition9 Declaring and Initializing a Two- Dimensional
Array (contd.) You initialize elements in a two-dimensional array
by entering a separate initialValues section, enclosed in braces,
for each row of the array Maximum number of initialValues sections
you may enter is the number of rows in the array Within individual
initialValues sections, you enter one or more values separated by
commas Maximum number of values you may enter in a row is the
number of columns An Introduction to Programming with C++, Sixth
Edition10 An Introduction to Programming with C++, Sixth Edition11
Figure 12-3 How to declare and initialize a two-dimensional array
An Introduction to Programming with C++, Sixth Edition12 Declaring
and Initializing a Two- Dimensional Array (contd.) Figure 12-4
Illustration of the two-dimensional grades array An Introduction to
Programming with C++, Sixth Edition13 Entering Data into a
Two-Dimensional Array You can use either an assignment statement or
the extraction operator to enter data into the elements of a
two-dimensional array Syntax for assignment statement: arrayName
[rowSubscript] [columnSubscript ] = expression; expression can
include any combination of constants, variables, and operators Must
match data type of array An Introduction to Programming with C++,
Sixth Edition14 Entering Data into a Two-Dimensional Array (contd.)
Syntax for extraction operator: cin >> arrayName
[rowSubscript][columnSubscript ]; An Introduction to Programming
with C++, Sixth Edition15 Figure 12-5 How to use an assignment
statement to assign data to a two-dimensional array An Introduction
to Programming with C++, Sixth Edition16 Figure 12-5 How to use an
assignment statement to assign data to a two-dimensional array
(contd.) An Introduction to Programming with C++, Sixth Edition17
Figure 12-6 How to use the extraction operator to store data in a
two-dimensional array An Introduction to Programming with C++,
Sixth Edition18 Figure 12-6 How to use the extraction operator to
store data in a two-dimensional array (contd.) An Introduction to
Programming with C++, Sixth Edition19 Displaying the Contents of a
Two- Dimensional Array To display the contents of a two-dimensional
array, you must access its individual elements You can use two
counter-controlled loops One to keep track of the row subscript One
to keep track of the column subscript An Introduction to
Programming with C++, Sixth Edition20 Figure 12-7 How to display
the contents of a two-dimensional array An Introduction to
Programming with C++, Sixth Edition21 Figure 12-7 How to display
the contents of a two-dimensional array (contd.) An Introduction to
Programming with C++, Sixth Edition22 Coding the Caldwell Companys
Orders Program Program that uses a two-dimensional array to store
the number of orders received from each of the Caldwell Companys
four sales regions during the first three months of the year Each
row in the array represents a region, and each column represents a
month Program allows the user to enter the order amounts and then
displays the amounts on the computer screen An Introduction to
Programming with C++, Sixth Edition23 Coding the Caldwell Companys
Orders Program Figure 12-8 IPO chart information and C++
instructions for the Caldwell Companys orders program An
Introduction to Programming with C++, Sixth Edition24 Figure 12-8
IPO chart information and C++ instructions for the Caldwell
Companys orders program (contd.) An Introduction to Programming
with C++, Sixth Edition25 Figure 12-9 The Caldwell Companys orders
program An Introduction to Programming with C++, Sixth Edition26
Figure Sample run of the Caldwell Companys orders program An
Introduction to Programming with C++, Sixth Edition27 Accumulating
the Values Stored in a Two-Dimensional Array Program for the Jenko
Booksellers company uses a two-dimensional array to store the sales
made in each of the companys three bookstores Array contains three
rows and two columns First column contains sales amount for
paperback books sold in each of three stores Second column contains
sales amounts for hardcover books in the three stores Program
calculates total sales by accumulating amounts stored in array and
displays total sales An Introduction to Programming with C++, Sixth
Edition28 Figure Problem specification, IPO chart information, and
C++ instructions for the Jenko Booksellers program An Introduction
to Programming with C++, Sixth Edition29 Figure Problem
specification, IPO chart information, and C++ instructions for the
Jenko Booksellers program (contd.) Accumulating the Value Stored in
a Two-Dimensional Array (contd.) An Introduction to Programming
with C++, Sixth Edition30 Figure The Jenko Booksellers program An
Introduction to Programming with C++, Sixth Edition31 Figure Result
of running the Jenko Booksellers program Accumulating the Value
Stored in a Two-Dimensional Array (contd.) An Introduction to
Programming with C++, Sixth Edition32 Searching a Two-Dimensional
Array Program for the Wilson Company uses a four-row, two-column
array to store the companys four pay codes and their corresponding
pay rates Pay codes are stored in first column of each row Pay rate
associated with each code is stored in the same row as its pay
code, in the second column Program gets a pay code from user and
searches for pay code in the arrays first column If pay code is
found, corresponding pay rate is displayed; otherwise, Invalid pay
code is displayed An Introduction to Programming with C++, Sixth
Edition33 Figure Problem specification, IPO chart information, and
C++ instructions for the Wilson Company program An Introduction to
Programming with C++, Sixth Edition34 Figure Problem specification,
IPO chart information, and C++ instructions for the Wilson Company
program (contd.) An Introduction to Programming with C++, Sixth
Edition35 Figure Problem specification, IPO chart information, and
C++ instructions for the Wilson Company program (contd.) An
Introduction to Programming with C++, Sixth Edition36 Figure Sample
run of the Wilson Company program Figure Another sample run of the
Wilson Company program An Introduction to Programming with C++,
Sixth Edition37 Figure Wilson Company program An Introduction to
Programming with C++, Sixth Edition38 Figure Wilson Company program
(contd.) An Introduction to Programming with C++, Sixth Edition39
Figure Desk-check table after the statements on lines 11 through 21
are processed Searching a Two-Dimensional Array (contd.) An
Introduction to Programming with C++, Sixth Edition40 Figure
Desk-check table after the nested loop is processed the first time
Searching a Two-Dimensional Array (contd.) An Introduction to
Programming with C++, Sixth Edition41 Figure Desk-check table after
the nested loop is processed the second time Searching a
Two-Dimensional Array (contd.) An Introduction to Programming with
C++, Sixth Edition42 Figure Desk-check table after the nested loop
ends during the second search Searching a Two-Dimensional Array
(contd.) An Introduction to Programming with C++, Sixth Edition43
Passing a Two-Dimensional Array to a Function Like one-dimensional
arrays, two-dimensional arrays are passed automatically by
reference When passing a two-dimensional array to a function,
function header and prototype should contain formal parameter
consisting of name of array followed by two sets of square brackets
containing the number of rows and columns, respectively Number of
rows is not required (first set of brackets may be left empty) An
Introduction to Programming with C++, Sixth Edition44 Figure
Modified Caldwell Companys orders program An Introduction to
Programming with C++, Sixth Edition45 Figure Modified Caldwell
Companys orders program (contd.) Summary A two-dimensional array
resembles a table in that elements are in rows and columns Each
element has the same data type You can determine the number of
elements in a two- dimensional array by multiplying the number of
rows by the number of columns Each element in a two-dimensional
array is identified by a unique combination of two subscripts
representing the elements row and column, respectively An
Introduction to Programming with C++, Sixth Edition46 Summary
(contd.) You refer to each element in a two-dimensional array by
the arrays name immediately followed by the elements subscripts in
two sets of square brackets First row and column subscripts in a
two- dimensional array are 0 Last row and column subscripts are
always one number less than the number of rows and columns,
respectively You must declare a two-dimensional array before you
can use it An Introduction to Programming with C++, Sixth Edition47
Summary (contd.) When declaring a two-dimensional array, you must
provide the number of rows as well as the number of columns You can
use an assignment statement or the extraction operator to enter
data into an array You need to use two loops to access every
element in a two-dimensional array One of the loops keeps track of
the row subscript, and the other keeps track of the column
subscript An Introduction to Programming with C++, Sixth Edition48
Summary (contd.) To pass a two-dimensional array to a function, you
include the arrays name in the statement that calls the function
Arrays corresponding formal parameter in the function header must
specify the formal parameters data type and name, followed by two
sets of square brackets First bracket contains the number of rows,
and the second bracket contains the number of columns An
Introduction to Programming with C++, Sixth Edition49 Lab 12-1:
Stop and Analyze Study the program in Figure and then answer the
questions The company array contains the amounts the company sold
both domestically and internationally during the months January
through June The first row contains the domestic sales for the
three months The second row contains the international sales during
the same period An Introduction to Programming with C++, Sixth
Edition50 Lab 12-2: Plan and Create Plan and create a program for
Falcon Incorporated Program should display a shipping charge based
on number of items ordered (entered by user) An Introduction to
Programming with C++, Sixth Edition51 Figure Problem specification
for Lab 12-2 Lab 12-3: Modify Modify the program in Lab 12-2
Replace the maximum amounts in the shipCharges array with the
minimum amounts Make the appropriate modifications to the program
Run and test the program appropriately An Introduction to
Programming with C++, Sixth Edition52 Lab 12-4: Desk-Check
Desk-check the Jenko Booksellers program in Figure An Introduction
to Programming with C++, Sixth Edition53 Lab 12-5: Debug Open the
program in the Lab12-5.cpp file Debug the program An Introduction
to Programming with C++, Sixth Edition54
