The following function writes a struct to a file.

int btwrite(short rrn, BTPAGE *page_ptr)
{
    long addr;
    addr = (long) rrn * (long) PAGESIZE + HEADERSIZE;
    lseek(btfd, addr, 0);
    return (write(btfd, page_ptr, PAGESIZE));
}

The following is the struct.

typedef struct {
    short keycount;             /* number of keys in page   */
    int  key[MAXKEYS];              /* the actual keys      */
    int  value[MAXKEYS];            /* the actual values        */
    short child[MAXKEYS+1];     /* ptrs to rrns of descendants  */
} BTPAGE;

What would happen if I changed the struct to a class, would it still work the same?

If I added class functions, would the size it takes up on disk increase?