C program....why does this program returns size 8?

Question

Sizeof structure
https://code.sololearn.com/cSFHc6nV4By9/?ref=app

Answer 1

An integer has 4 bytes = 32 bits. Your struct uses 5 bits of an unsigned int for d and 4 bits for m. d + m need only 9 bits, so they can be stored in one int. y is another int so the struct has two integers in total. 2 integers = 8 bytes

Answer 2

Very cool, I didn't know one can specify the number of bits explicitely 😱

Answer 3

Matthias Those are called bit fields

https://www.tutorialspoint.com/cprogramming/c_bit_fields.htm

Answer 4

Thank you!