Topic 9C –
Multiple Dimension Arrays
Multiple Dimension Arrays
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A multiple dimension array is an array that
has two or more dimensions.
Two dimensional arrays are the simplest type
of multiple dimension arrays. They can be
used to represent tables of data, matrices,
and other two dimensional objects.
One of the most obvious example of a two
dimensional array is the tic-tac-toe board.
CISC105 – Topic 9C
Multiple Dimension Arrays
Example: Tic-Tac-Toe
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A tic-tac-toe board has two dimensions,
the row and the column. Each dimension
is composed of 3 possible indices (there
are 3 rows and 3 columns).
0
1
2
0
[0][0]
[0][1]
[0][2]
1
[1][0]
[1][1]
[1][2]
2
[2][0]
[2][1]
[2][2]
CISC105 – Topic 9C
Two Dimensional Arrays
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We can see how a two dimensional
array looks like a table or matrix.
Thus, we can represent a two
dimensional array as rows and columns.
To declare a two-dimensional array:
(data type) array_name[# of rows][# of columns];
CISC105 – Topic 9C
Two Dimensional
Arrays Declarations
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Therefore, a two dimensional array of
integers, named x, with 29 rows and 33
columns would be declared as:
int x[29][33];
A two dimensional array of characters,
named c, with 119 rows and 2 columns
would be declared as:
char c[119][2];
CISC105 – Topic 9C
Multiple Dimension
Array Declarations
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We can also declare arrays of more
than two dimensions. A six dimensional
array of doubles could be declared as:
double a[2][3][9][4][5][3];
A three dimensional array of integers
could be declared as:
int x[4][5][4];
CISC105 – Topic 9C
Referencing Multiple
Dimension Arrays
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To access an element of a multiple
dimension array, we use the same form
as for one dimensional arrays, with the
extra dimension(s) also present, such
as:
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x[2][7] = x[1][7] + 27;
y[9][2][0][4] = 9;
printf(“%d”,p[3][4][5][9][0]);
CISC105 – Topic 9C
Multiple Dimension Arrays
as Function Arguments
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We have seen that when one dimensional
arrays are passed into a function, the size of
the array is not passed in. This allows us to
pass arrays of any size into the function.
When passing a multiple dimension array as a
function parameter, the size MUST BE
specified in the function prototype.
Thus, we can only pass in fixed-size multiple
dimensional arrays into functions.
CISC105 – Topic 9C
Multiple Dimension Arrays
as Function Arguments
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However, there is one exception to this rule.
The FIRST size (in a two dimensional array,
the number of rows) MAY be omitted in a
function prototype.
Therefore, if we wanted to create a function
that takes one parameter, a tic-tac-toe board,
we could write the prototype as either:
void function_x(char board[][3]);
OR
void function_x(char board[3][3]);
CISC105 – Topic 9C
Multiple Dimension Arrays
as Function Arguments
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If the size of a multiple dimension array
is known and fixed, such as the size of
a tic-tac-toe board, the size of all
dimensions should be specified.
If this is not fixed, or known, the first
dimension can, and should, be omitted.
CISC105 – Topic 9C
Multiple Dimension Arrays as
Function Arguments
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Thus, the following function prototypes
are valid:
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void function_a(char[][4]);
int function_b(int[4][9]);
int function_c(char p[3][9][2]);
int function_d(int[][9][2][4]);
int function_e(int[4][9][2][4]);
int function_f(char[][3][9]);
CISC105 – Topic 9C
Multiple Dimension Arrays as
Function Arguments
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In contrast, the following function
prototypes are NOT valid:
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void function_a(char[][]);
int function_b(int[4][]);
int function_c(char p[][][2]);
int function_d(int[][9][][]);
int function_e(int[4][][4][]);
int function_f(char[9][][9]);
CISC105 – Topic 9C
Initialization of
Multiple Dimension Arrays
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Multiple dimension arrays can be
initialized in much the same way as one
dimensional arrays.
char board[3][3] = { {‘X’, ‘X’, ‘O’},
{‘O’, ‘X’, ‘O’},
{‘X’, ‘O’, ‘X’} };
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Notice how the initialization list is
grouped into rows.
CISC105 – Topic 9C
Initialization of
Multiple Dimension Arrays
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In addition to grouping the initialization
list into rows, the initialization list can
simply be provided as a straight list:
char board[3][3] = {‘X’,‘X’,‘O’,‘O’,‘X’,
‘O’,‘X’,‘O’,‘X’};
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This type of initialization list fills in the
first row, left-to-right, then the second
row, left-to-right, then the third row,
etc…
CISC105 – Topic 9C
Initialization of
Multiple Dimension Arrays
char board[3][3] = {‘X’,‘X’,‘O’,‘O’,‘X’,
‘O’,‘X’,‘O’,‘X’};
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Thus, this declaration will set
board[0][0] to ‘X’, board[0][1] to ‘X’,
board[0][2] to ‘O’, board[1][0] to ‘O’,
board[1][1] to ‘X’, board[1][2] to ‘O’,
board[2][0] to ‘X’, board[2][1] to ‘O’,
board[2][2] to ‘X’.
CISC105 – Topic 9C
Summary
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Multiple dimension arrays are very similar to
one dimensional arrays, in declarations,
initialization, and referencing.
When passing a multiple dimension array into
a function, the size of the dimensions MUST
be specified (in contrast to one dimensional
arrays), with the exception of the size of the
first array dimension.
CISC105 – Topic 9C
An Example Problem #1
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Write a prototype for a function named
function1 that takes two parameters, a
three dimensional integer array with sizes 4,
9,
&
10,
and
a
four
dimensional
integer
array
float function1(
const int array1[4][9][10],
with sizes 9, 4, 2,int&array2[9][4][2][2]
2. The first array is );for
input and the function should not be able to
modify it. The second array is for input and
output; the function can modify it. The
function returns a float data type.
CISC105 – Topic 9C
An Example Problem #2
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Write a function that takes one parameter, a
tic-tac-toe board. It should then ask the user
which box they want to put a ‘X’ in, by
specifying the row and column. The function
should then set that specified box equal to ‘X’.
The prototype for this function is given:
void set_an_X(char board[3][3]);
CISC105 – Topic 9C