Binary data with struct in Python

Packing and unpacking C-style binary records.

import struct

packet = struct.pack(">HHI", 80, 443, 1500)
size = struct.calcsize(">HHI")

src_port, dst_port, length = struct.unpack(">HHI", packet)

record = struct.pack("<f?", 3.14, True)
pi, flag = struct.unpack("<f?", record)

header = struct.Struct(">4sB")
blob = header.pack(b"TYPE", 7)

How it works

1. Format codes like >HHI set order and field types.
2. pack builds bytes; unpack reverses it.
3. A Struct object reuses a compiled format.

The run, in numbers

Lines

12

Characters to type

293

Tokens

95

Three-star pace

110 tpm

At the three-star pace of 110 tokens a minute, this run takes about 52 seconds.

Type this snippet

Step 5 of 5 in Data formats, step 21 of 41 in Domain tools.

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