UMBC CS 201, Fall 06
Multi-dimensional Arrays as Parameters
Example prototypes
For a 2-dimensional array:
void Print2DArray(int a[][5], int rows, int cols);
or
void Print2DArray(int a[7][5], int rows, int cols);
For a 3-dimensional array:
void Print3DArray(int a[][6][4], int x, int y, int z);
or
void Print3DArray(int a[7][6][4], int x, int y, int z);
Notice that all but the first square bracket must show the size of the
dimension. The first square bracket may optionally contain the size of
first dimension as well.
What gets passed ?
Just like one-dimensional arrays, the address of the base of the array.
The Program
<![CDATA[
/*************************************************
* Filename: passing2d.c
* Author: Sue Bogar
* Date Written: 2/25/98
* Section: 101
* EMail: bogar@cs.umbc.edu
* Modified by: Sue Evans
* Mod. date: 2/21/04
* Mod reason: To meet current 201 standards
*
* This program was designed to show an example
* of passing a two-dimensional array to a
* function
*************************************************/
#include <stdio.h>
#define ROWS 7
#define COLS 5
/* Example prototype of a function that takes an
** array as an argument. NOTE: the empty square
** brackets for the first dimension. You can
** optionally put the size within the brackets. */
void FillArray (int array[][COLS], int rows, int cols);
float FindMean (int array[ROWS][COLS], int rows, int cols);
void PrintArray (int array[ROWS][COLS], int rows, int cols);
int main ( )
{
int array[ROWS][COLS];
float mean;
FillArray (array, ROWS, COLS);
mean = FindMean (array, ROWS, COLS);
PrintArray (array, ROWS, COLS);
printf ("\nThe mean of all the values is %.2f\n", mean);
return 0;
}
/*********************************************************
* Function: FillArray()
*
* FillArray() fills each element in the 2-dimensional
* array passed in with the product of each elements'
* indices.
*
* Input: a two-dimensional array of ints,
* the number of rows & the number of columns
* Output: there is no return value
*********************************************************/
void FillArray (int array[][COLS], int rows, int cols)
{
int i, j;
/* Assign each element the value of the
product of the two indices */
for (i = 0; i < rows; i++)
{
for (j = 0; j < cols; j++)
{
array[i][j] = i * j;
}
}
}
/*********************************************************
* Function: FindMean()
*
* FindMean() calculates the mean of the values stored in
* the 2-dimensional array passed in.
*
* Input: a two-dimensional array of ints, the number
* of rows & the number of columns
* Output: returns the (float) mean of all the
* elements in the array.
********************************************************/
float FindMean (int array[ROWS][COLS], int rows, int cols)
{
int i, j, num;
float mean, total = 0.0;
/* Find the sum of all the elements */
for (i = 0; i < rows; i++)
{
for (j = 0; j < cols; j++)
{
total += array[i][j];
}
}
/* Calculate number of elements */
num = rows * cols;
/* Find the mean */
mean = total/num;
return mean;
}
/*********************************************************
* Function: PrintArray()
*
* PrintArray() prints the values stored in a 2-dimensional
* array of ints in tabular form.
*
* Input: a two-dimensional array of ints, the number of
* rows & the number of columns
* Output: there is no return value
*********************************************************/
void PrintArray (int array[ROWS][COLS], int rows, int cols)
{
int i, j ;
for (i = 0; i < rows; i++)
{
for (j = 0; j < cols; j++)
{
printf ("%4d", array[i][j]);
}
printf ("\n");
}
}
]]>
The Sample Run
<![CDATA[
linux1[109] % a.out
0 0 0 0 0
0 1 2 3 4
0 2 4 6 8
0 3 6 9 12
0 4 8 12 16
0 5 10 15 20
0 6 12 18 24
The mean of all the values is 6.00
linux1[110] %
]]>
Last Modified - Tuesday, 22-Aug-2006 07:13:58 EDT
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