4.3 The struct Module

The struct module shown in Example 4-6 contains functions to convert between binary strings and Python tuples. The pack function takes a format string and one or more arguments, and returns a binary string. The unpack function takes a string and returns a tuple.

Example 4-6. Using the struct Module

File: struct-example-1.py

import struct

# native byteorder
buffer = struct.pack("ihb", 1, 2, 3)
print repr(buffer)
print struct.unpack("ihb", buffer)

# data from a sequence, network byteorder
data = [1, 2, 3]
buffer = apply(struct.pack, ("!ihb",) + tuple(data))
print repr(buffer)
print struct.unpack("!ihb", buffer)

# in 2.0, the apply statement can also be written as:
# buffer = struct.pack("!ihb", *data)

'\001\000\000\000\002\000\003'
(1, 2, 3)
'\000\000\000\001\000\002\003'
(1, 2, 3)