Inheritance in C, struct as pure superset of another struct

base.c

#include "base.h"
#include <stdio.h>

struct Device {
    int serial_number;
    int sizeof_memory;
};

void print_values( struct Device * some_device ) {
    printf("Serial number: %d, ", some_device->serial_number);
    printf("memory size = %d\n", some_device->sizeof_memory);
}

base.h

#ifndef BASE_H
#define BASE_H

struct Device;
void print_values( struct Device * some_device );

#endif /* BASE_H */

derived.c

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

struct Computer {
    int serial_number;
    int sizeof_memory;
    char nameof_os[10];
};

struct Computer * create_computer() {
    struct Computer * some_computer;
    some_computer = malloc(sizeof(struct Computer));
    some_computer->serial_number = 12345678;
    some_computer->sizeof_memory = 87654321;
    strcpy(some_computer->nameof_os , "Windows 95");
    return( some_computer );
}

void print_os( struct Computer * some_computer ) {
    printf("OS is: %s\n", some_computer->nameof_os);
}

void delete_computer( struct Computer * some_computer ) {
    free(some_computer);
}

derived.h

#ifndef DERIVED_H
#define DERIVED_H

struct Computer;

struct Computer * create_computer();
void print_os( struct Computer * some_computer );
void delete_computer( struct Computer * some_computer );

#endif /* DERIVED_H */

main.c

#include "base.h"
#include "derived.h"

int main() {
    struct Computer * My_computer;

    My_computer = create_computer();
    print_os( My_computer );

    // note typecasting here
    print_values(( struct Device * ) My_computer );

    delete_computer( My_computer );
    return 0;
}