Tom Lin wrote:
> But one precondition is not to use int(string, base). How would you
> implement the conversion?
It's not hard. You have two choices: each character of the string
represents a bit, and should be either a "0" or a "1" (anything else is
an error). In which case its numeric value is either 0 or 1.
if bit == '0': value = 0
elif bit == '1': value = 1
else: raise ValueError("not a binary IP address")
If you are allowed to assume that the characters will only by 0 or 1,
and that there will never be anything else, you can do something even
smarter and faster. Here's a clue:
>>> total = 0
>>> s = "abaa"
>>> for c in s:
... total += (c == "a")
...
>>> total
3
The boolean flags True and False are actually disguised numbers with
values 1 and 0.
--
Steven
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