pack.calcsize('1b1I') = 1+4=8 !?

[VladVons]

Code: Select all

    # size of byte is 1
    print(struct.calcsize('1b'))
    1

    # size of integer is 4
    print(struct.calcsize('1I'))
    4

    # size of byte + integer should be 5, but got 8
    print(struct.calcsize('1b1I'))
    8

[jimmo]

Please see https://docs.python.org/3/library/struc ... -alignment

Your example is the same as using the @ specifier, which means "native" alignment, hence it works like a regular C struct, where each member will be aligned.

Use the < or > specifier (which you should do anyway to be clear about which endianness you're using)

Code: Select all

print(struct.calcsize('<1b1I'))
5

[VladVons]

oh yep, thanks!