[Tutor] Count for loops

[eryk sun]

On Wed, Apr 12, 2017 at 4:03 AM, boB Stepp <robertvstepp at gmail.com> wrote:
>
> I have not used the decimal module (until tonight).  I just now played
> around with it some, but cannot get it to do an exact conversion of
> the number under discussion to a string using str().

Pass a string to the constructor:

    >>> d = decimal.Decimal('3.14159265358979323846264338327950288419716939')
    >>> str(d)
    '3.14159265358979323846264338327950288419716939'

When formatting for printing, note that classic string interpolation
has to first convert the Decimal to a float, which only has 15 digits
of precision (15.95 rounded down).

    >>> '%.44f' % d
    '3.14159265358979311599796346854418516159057617'
    >>> '%.44f' % float(d)
    '3.14159265358979311599796346854418516159057617'

The result is more accurate using Python's newer string formatting
system, which allows types to define a custom __format__ method.

    >>> '{:.44f}'.format(d)
    '3.14159265358979323846264338327950288419716939'
    >>> format(d, '.44f')
    '3.14159265358979323846264338327950288419716939'