Python's `struct` byte size calcualtion

Question

Unfortunately I don't understand the byte size calculation of the struct python module. I use this documentation when encoding my values.

import struct
struct.calcsize('H') # == 2
struct.calcsize('d') # == 8

but

struct.calcsize('Hd') # == 16 != 8+2

using the encoding together requires 16 bytes instead of 10

What could be/is the reason for this? Thanks!

• Michael Butscher: See the grey "note" box at the beginning of your linked documentation page about alignment.
• gre_gor: Does this answer your question? Python struct giving incorrect length

Answer 1

Maybe this can help; Python struct giving incorrect length

struct.calcsize('=Hd')

• Drey: Thank you and thanks also to @Michael Butscher for the hint.