Two ways to reach a tray

trays is an array, not a pointer variable. In most expressions, its name converts to the address of element 0. Adding 1 moves that pointer by one int element, making *(trays + 1) another way to read trays[1]. You may form a pointer just past the end of the array, but you cannot dereference it or move it farther.

#include <stdio.h>

int main(void) {
    int trays[] = {3, 5, 7};
    int *cursor = trays;
    printf("First: %d\n", *cursor);
    cursor++;
    printf("Second: %d\n", *cursor);
    printf("Same element: %d\n", trays[1]);
    return 0;
}

The first access reads index 0; after incrementing, cursor points at index 1. The array still has three elements and cannot be assigned a new address with trays = cursor. Change the second element and predict which printed lines change. For the exercise, you will move through four elements while keeping track of the length.