Iterating over neighbours in a multi-dimensional array in C

8_neighbours.c

4_neighbours.c

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

int main(int argc, char* argv[]) {
    int arr[][5] = {
        {1, 2, 3, 4, 5},
        {1, 2, 3, 4, 5},
        {1, 2, 3, 4, 5},
        {1, 2, 3, 4, 5},
        {1, 2, 3, 4, 5},
    }
    int offsetx[] = { 0,  1, 1, 1, 0, -1, -1, -1};
    int offsety[] = {-1, -1, 0, 1, 1,  1,  0, -1};
    
    int x, y;
    printf("Input x: ");
    scanf("%d", &x);
    printf("Input y: ");
    scanf("%d", &y);
    
    int i;
    int sum = arr[y][x];
    for (i = 0; i < 8; i++) {
        int nx = x + offsetx[i];
        int ny = y + offsety[i];
        if (nx < 0 || nx > 4 || ny < 0 || ny > 4) {
            continue;
        }
        sum += arr[ny][nx];
    }
    printf("The sum of neighbours is %d\n", sum);
    return 0;
}