non 0 based

//-std=c99 -Wall -Wextra -Wpedantic -Wshadow

#include <stdio.h>
#include <stdlib.h>

int main (int argc, char **argv){

    //it is illegal to refer to objects that are not within the array bounds

    int arr[]={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21};
    int* tmp;

    tmp = arr;

    tmp-=10;

    printf("%d\n",tmp[10]);

    tmp+=21;

    printf("%d\n",tmp[0]);
    printf("%d\n\n",tmp[-1]);

    //http://c-faq.com/aryptr/non0based.html

    //int realarray[10];
    int realarray[10]={1,2,3,4,5,6,7,8,9,0};
    int *array = &realarray[-1];

    printf("%p\n",(void*)realarray);
    printf("%p\n",(void*)array);

    printf("%d\n",array[1]);

return 0;
}

/*
output:

1
12
11

0x7fff69ae6830
0x7fff69ae682c
1

*/