Multiple-Subscripted%20Array

1
Multiple-Subscripted Array

• What it is
• How to use it
• How to declare it
• How to initialize it

2
Multiple-Subscripted Arrays

• Use more than one subscript (can have up to 12)
• Double-subscripted array (2 subscripts)

3
Double-subscripted array

• good for representing tables in memory
• one subscript is the row
• second subscript is the column

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Double-subscripted array
column 0
column 1
column 2
column 3
row 0
a00
a01
a02
a03
row 1
a10
a11
a12
a13
a20
a21
a22
a23
row 2
column subscript
row subscript
array name a
a double-subscripted array with 3 rows and 4
columns 3 by 4
array
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Referencing elements in a double-subscripted array
To set the element in row 2 and column 3 to the
value 4 use a 2 3 4
column subscript
row subscript
name of the array
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Declaring a 3 by 4 array
int a 3 4
must tell compiler name, size (2 sizes) and
type all elements of the array must be the same
type any data type is fine (int, float, char,
etc.)
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Declaring a double-subscripted array
Must use constants to declare row and column
sizes. int a 3 4 char letters 2 26
define ROW 3 define COLUMN 4 int a ROW
COLUMN const int row 3 const int column
4 int a row column
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Initializing a double-subscripted array
const int row 3 const int column 4 int a
row column for (int i 0 i lt row i)
for (int j 0 j lt column j) a
ij 0
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Initializing a double-subscripted array with
declaration
const int row 3 const int column 4 int
arow column 1,2,3,4,
1,2,3,4,
1,2,3,4
2
3
4
1
3
1
2
4
3
4
1
2
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Initializing a double-subscripted array with
declaration
const int row 3 const int column 4 int
arow column 1,2,3,
1,2,
1,2,3,4
2
3
0
1
0
1
2
0
3
4
1
2
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Setting entire array to 0
const int row 3 const int column 4 int a
row column 0
0
0
0
0
0
0
0
0
0
0
0
0
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Exercises
Answer the following questions regarding an array
called table that is a double-subscripted array
with 2 rows and 3 columns. 1) Define constant
variables numRows and numCols to be used to
declare the array. 2) Declare the array to be
an integer array. 3) Use a for loop to
initialize each element of the array to be the
sum of its subscripts 4) Write a code segment
to print the array as a table.
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How double-subscripted arrays are stored in memory
2
3
4
1
table
5
6
7
8
9
10
11
12
table
1
2
3
4
5
6
7
8
9
10
11
12
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passing double-subscripted array to a function
Must tell function size of second subscript so it
can find the beginning of each row in memory.
void PrintTable (int table 4, int
numRows, int numCols) for (int i 0 i lt
numRows i) for (int j 0 j lt
numCols j) cout ltlt setw(4) ltlt table
i j cout ltlt endl
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passing double-subscripted array to a function

• passed as reference parameter
• Use const to prevent function changing the array.

void PrintTable (const int table 4, int
numRows, int numCols)
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Exercises
Write a main program as follows Use the results
of the last set of exercises to declare an array
of type integers with 2 rows and 3 columns and
initialize each element to the sum of its
subscripts. Call the PrintTable function to print
the array. Create a function called PrintTable
to print each element of the array in tabular
form.