Why can't I make an array of structs with bitfield?

I’m currently learning about unions in C99. The task was to read an int by user, and then display it as:

• 2x word
• 4x bytes
• 4x 8 bits (4 octets from Most Significant Bit, to Least Significant Bit)

without using bitwise operators,

without using [] operator to read arrays,

using only one if (ternary op. is forbidden).

My solution passes the tests fine, but I wanted to ask if there is any way to make it more compact in displaying the bit values.

My solution was this:

#include <stdio.h>

struct byte{
    unsigned char bit0:1;
    unsigned char bit1:1;
    unsigned char bit2:1;
    unsigned char bit3:1;
    unsigned char bit4:1;
    unsigned char bit5:1;
    unsigned char bit6:1;
    unsigned char bit7:1;
};

union bit_set{
    unsigned int number;
    unsigned short word[2];
    unsigned char byte[4];
    struct byte bytes[4];
};

int main() {
    union bit_set bit_set = {0};
    setvbuf(stdout, NULL, _IONBF, 0);
    printf("Podaj liczbę: ");
    if(!scanf("%u", &bit_set.number)){
        printf("Incorrect input");
        return 1;
    }
    printf("%u\n", bit_set.number);
    printf("%d %d\n", *bit_set.word, *(bit_set.word+1));
    printf("%d %d %d %d\n", *bit_set.byte, *(bit_set.byte+1), *(bit_set.byte+2), *(bit_set.byte+3));
    for(int i = 0; i < 4; i++){
        printf("%d", (bit_set.bytes+i)->bit7);
        printf("%d", (bit_set.bytes+i)->bit6);
        printf("%d", (bit_set.bytes+i)->bit5);
        printf("%d", (bit_set.bytes+i)->bit4);
        printf("%d", (bit_set.bytes+i)->bit3);
        printf("%d", (bit_set.bytes+i)->bit2);
        printf("%d", (bit_set.bytes+i)->bit1);
        printf("%d", (bit_set.bytes+i)->bit0);
        printf(" ");
    }

    return 0;
}

My guess to make it more compact:

struct byte{
    unsigned char bit0:1;
};

union bit_set{
    unsigned int number;
    unsigned short word[2];
    unsigned char byte[4];
    struct byte bits[32];
};

// ...

   for(int i = 0; i < 4; i++){
        for (int j = 7; j > 0; j--) {
            printf("%d", (bit_set.bits+j)->bit0);
        }
        printf(" ");
    }

The "compact" code above does not produce any good results. For inputs:

Enter a number: 1

it produces:

1
1 0
1 0 0 0
0000000 0000000 0000000 0000000

Example 2:

Enter a number: 2

it produces:

2
2 0
2 0 0 0
0000000 0000000 0000000 0000000

>Solution :

In C, a struct object has a minimum size of 1 byte.

Therefore, in the code

struct byte{
    unsigned char bit0:1;
};

union bit_set{
    unsigned int number;
    unsigned short word[2];
    unsigned char byte[4];
    struct byte bits[32];
};

the member bits is an array of 32 elements of struct byte, in which each element has a size of 1 byte. The total size of that array is therefore 32 bytes. You seem to expect the size of the array to be 32 bits, i.e. 4 bytes.