Challenge 2: Round-Tripping an int Array Through Binary File I/O — Possible Solution
====================================================================

#include <stdio.h>

int main() {
    int original[5] = {10, 20, 30, 40, 50};

    FILE *out = fopen("nums.bin", "wb");
    if (out == NULL) {
        return 1;
    }
    fwrite(original, sizeof(int), 5, out);
    fclose(out);

    int loaded[5];
    FILE *in = fopen("nums.bin", "rb");
    if (in == NULL) {
        return 1;
    }
    fread(loaded, sizeof(int), 5, in);
    fclose(in);

    printf("original: ");
    for (int i = 0; i < 5; i++) printf("%d ", original[i]);
    printf("\nloaded:   ");
    for (int i = 0; i < 5; i++) printf("%d ", loaded[i]);
    printf("\n");

    return 0;
}

Output:

    original: 10 20 30 40 50
    loaded:   10 20 30 40 50

WHY THIS WORKS AS AN ANSWER
------------------------------
Both fopen calls use the binary-mode "wb"/"rb" variants, exactly the
mode pairing the chapter specifies for raw byte transfer with no
text-mode line-ending translation risk, and fwrite/fread are both
called with matching sizeof(int) element size and count (5) --
confirmed correct by printing both arrays and observing them match
exactly.