An example of array initialization in C

sloth

This example program illustrates array initialization in C.

#include <stdio.h>

#define ARRAY_SIZE 10

int main ()
{
    int i;
    /* Initialize all the elements. */
    int array_all[ARRAY_SIZE] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
    /* If only the first elements are initialized, the remaining
       elements are all set to zero. */
    int array_first_two[ARRAY_SIZE] = { 1, 2 };
    /* So, if the first element is set to zero, then everything else
       is, too. */
    int array_zero[ARRAY_SIZE] = { 0 };
    /* But if nothing is initialized, the whole array contains random
       junk. */
    int array_not_static[ARRAY_SIZE];
    /* Unless the array is declared using "static", in which case it
       is zeroed. */
    static int array_static[ARRAY_SIZE];

    /* This prints out the contents of the arrays. */
    for (i = 0; i < ARRAY_SIZE; i++) {
        printf ("%2d: %2d %d %d %12d %d\n",
                i,
                array_all[i],
                array_first_two[i],
                array_zero[i],
                array_not_static[i],
                array_static[i]
                );
    }

    return 0;
}

(download)

It outputs something like

 0:  1 1 0    671490048 0
 1:  2 2 0    134519028 0
 2:  3 0 0    672654592 0
 3:  4 0 0    671478452 0
 4:  5 0 0  -1077942112 0
 5:  6 0 0    671401671 0
 6:  7 0 0    671481716 0
 7:  8 0 0  -1077942192 0
 8:  9 0 0  -1077942136 0
 9: 10 0 0            1 0

The numbers in the second-to-last column will vary each time it's run.


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