Example program to explain pointers to a friend

pointers.c

#include <stdio.h>

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


    int arr[10];
    int * arrptr;
    int x;
    int * xptr;

    printf("Size of a pointer: %lu\n", sizeof(xptr));
    printf("Size of an int: %lu\n\n", sizeof(x));

    printf("-- Memory positions --\n");
    printf("Value of '&arr': %p\n", &arr);
    printf("Value of '&arrptr': %p\n", &arrptr);
    printf("Value of '&x': %p\n", &x);
    printf("Value of '&xptr': %p\n", &xptr);
    printf("\n");

    arr[0] = 42;
    arrptr = arr;
    x = 1;
    xptr = &x;

    printf("-- Names values --\n");
    printf("Value of 'arr': %p\n", arr);
    printf("Value of 'arrptr': %p\n", arrptr);
    printf("Value of 'x': %d\n", x);
    printf("Value of 'xptr': %p\n", xptr);
    printf("\n");

    printf("-- Pointed by Names values --\n");
    printf("Value of '*arr': %d\n", *arr);
    printf("Value of '*arrptr': %d\n", *arrptr);
    printf("x is not a pointer");
    printf("Value of '*xptr': %d\n", *xptr);

    return 0;
}