Mailing List Archive: How to write list of integers to file with struct.pack

Jen Kris via Python-list schreef op 2/10/2023 om 17:06:
> My previous message just went up -- sorry for the mangled formatting. Here it is properly formatted:
>
> I want to write a list of 64-bit integers to a binary file. Every example I have seen in my research converts it to .txt, but I want it in binary. I wrote this code, based on some earlier work I have done:
>
>     buf = bytes((len(qs_array)) * 8)
>     for offset in range(len(qs_array)):
>         item_to_write = bytes(qs_array[offset])
>         struct.pack_into(buf, "<Q", offset, item_to_write)

Shouldn't the two first parameters be swapped, like this?

        struct.pack_into("<Q", buf, offset, item_to_write)

Also it wouldn't surprise me if you had to use offset*8 instead of just
offset in that pack_into() call -- I would think the offset is specified
in bytes.

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