Node:Arrays and nested loops, Next:Initializing arrays, Previous:Multidimensional arrays, Up:Arrays
To initialize multidimensional arrays, you can use nested for
loops. Three nested loops are needed to initialize a three-dimensional
array:
#include <stdio.h>
#define SIZE1 3
#define SIZE2 3
#define SIZE3 3
int main ()
{
int fast, faster, fastest;
int my_array[SIZE1][SIZE2][SIZE3];
for (fast = 0; fast < SIZE1; fast++)
{
for (faster = 0; faster < SIZE2; faster++)
{
for (fastest = 0; fastest < SIZE3; fastest++)
{
my_array[fast][faster][fastest] = 0;
printf("my_array[%d][%d][%d] DONE\n", fast, faster, fastest);
}
}
}
printf("\n");
}
In this example, the variables fast, faster, and
fastest contain the indices of the array, and vary fast, faster,
and fastest, respectively. In the example output below, you can see
that the fastest index changes every line, while the
faster index changes every three lines, and the fast index
changes only every nine lines.
my_array[0][0][0] DONE my_array[0][0][1] DONE my_array[0][0][2] DONE my_array[0][1][0] DONE my_array[0][1][1] DONE my_array[0][1][2] DONE my_array[0][2][0] DONE my_array[0][2][1] DONE my_array[0][2][2] DONE my_array[1][0][0] DONE my_array[1][0][1] DONE my_array[1][0][2] DONE my_array[1][1][0] DONE my_array[1][1][1] DONE my_array[1][1][2] DONE my_array[1][2][0] DONE my_array[1][2][1] DONE my_array[1][2][2] DONE my_array[2][0][0] DONE my_array[2][0][1] DONE my_array[2][0][2] DONE my_array[2][1][0] DONE my_array[2][1][1] DONE my_array[2][1][2] DONE my_array[2][2][0] DONE my_array[2][2][1] DONE my_array[2][2][2] DONE
Note: Although in this example we have followed the order in
which indices vary inside the computer, you do not have to do so in your own
code. For example, we could have switched the nesting of the innermost
fastest and outermost fast loops, and every element would
still have been initialized. It is better, however, to be systematic
about initializing multidimensional arrays.