how do i change sin_array initialisation or modification so the changes made to it in populate_array are global changes so i can use the modified sin_array in check_sin
#include <stdio.h>
#include <stdlib.h>

// TODO: Implement populate_array
/*
 * Convert a 9 digit int to a 9 element int array.
 */
int populate_array(int sin, int *sin_array) {
    int number_of_digits = 0;
    while(sin != 0){
        sin = sin / 10;
        number_of_digits ++;
    }

    if(number_of_digits != 9){
        return 1;
    } else {
        for(int i = 0; i < 9; i++){
            sin_array[i] = (sin / (10^(8 - i))) % 10;
        }
        return 0;
    }
}

// TODO: Implement check_sin
/*
 * Return 0 if the given sin_array is a valid SIN, and 1 otherwise.
 */
int check_sin(int *sin_array) {
    printf("%d", sin_array[0]);
    int mult_array[9] = {1, 2, 1, 2, 1, 2, 1, 2, 1};
    int total = 0;
    for(int i = 0; i<9; i++){
        if((sin_array[i] * mult_array[i]) / 10 == 0){
            total += (sin_array[i] * mult_array[i]);
            printf("%d\n", sin_array[i]*mult_array[i]);
        } else {
            int one = (sin_array[i] * mult_array[i]) / 10;
            int two = (sin_array[i] * mult_array[i]) % 10;
            total += (one + two);
            printf("%d\n", sin_array[i]*mult_array[i]);
        }
    }
    printf("%d\n", total);
    if(total % 10 == 0){
        return 0;
    } else {
        return 1;
    }
}

int populate_array(int, int *);
int check_sin(int *);


int main(int argc, char **argv) {
    // TODO: Verify that command line arguments are valid.

    // TODO: Parse arguments and then call the two helpers in sin_helpers.c
    // to verify the SIN given as a command line argument.

    if(argc != 2){
        return 2;
    } else {
        int sin_array[9];
        int is_nine = populate_array(atoi(argv[1]), sin_array);
        if(is_nine == 1){
            printf("%s", "Invalid SIN\n");
            return 1;
        }

        if(check_sin(sin_array) == 0){
            printf("%s","Valid SIN\n");
            return 0;
        } else {
            printf("%s","Invalid SIN\n");
            return 1;
        }
    }


}