Reading 3 bytes as an integer

Question

How can I read 3 bytes as an integer?

Does struct module provide something like that?

I can read in 3 bytes and add an extra \\x00 and then interpret it as a 4-b

Answer 1

An alternative for python 2 and without the struct module would be:

>>> s = '\x61\x62\xff'
>>> a = sum([ord(b) * 2**(8*n) for (b, n) in zip(s, range(len(s))[::-1])])
>>> print a
6382335

where the byte ordering is big-endian. This gives the same result as with unutbu answer:

>>> print struct.unpack('>I', '\x00' + s)[0]
6382335

For little-endian byte ordering the conversion would be:

>>> a = sum([ord(b) * 2**(8*n) for (b, n) in zip(s, range(len(s)))])
>>> print a
16736865
>>> print struct.unpack('