Inverse of int(s, base)?

[Paul Rubin]

danb_83 at yahoo.com (Dan Bishop) writes:
> >         while x:
> >                 result = str_digits[x % base] + result
> >                 x /= base
> 
> The above line should be "x //= base", so it works under -Qnew.

Or just say:
                   x, r = divmod(x, base)
                   result = result + str_digits[r]

> That works (for positive integers), but it might be more efficient to
> not create a new string each time through the loop.  An alternative is:
> 
> def str_base(n, base=10):
   ...

Similarly:

def str_base(n, base=10):
    results = []
    sign,n = ('','-')[n < 0], abs(n)
    while n:
        n, r = divmod(n, base)
        results.append(str_digits[r])
    results.reverse()
    return sign + ''.join(results)