Newbie Formatting Question

[Heather Coppersmith]

On Mon, 22 Mar 2004 16:33:34 GMT,
. <soyyo at NOSPAMterra.es> wrote:

> I'm going through "How to Think Like a Computer Scientist", and 
> am in chapter 11. (aside: what do you think of the book? any 
> recommendations for other books?)

Can't help here.

> print "%-20x %12.02f" % (student, wages[student])

> I understand what's going on, and the example works fine.  I
> just don't understand what the 0 is doing in the %12.02f format
> specification. I thought it might be to force padding zeroes,
> but I get the same result with or without the 0. Also, %12.0002f
> gives the same result. Was this a typo, or is there something
> that I'm not understanding?

The number after the decimal point is the number of digits that
should come out (surprise!) after the decimal point:

    >>> for x in range( 10 ):
         f = '%20.' + str( x ) + 'f' # or f = '%%20.%df' % x
         print f % 1.2

                       1
                     1.2
                    1.20
                   1.200
                  1.2000
                 1.20000
                1.200000
               1.2000000
              1.20000000
             1.200000000

The padding/filling comes for free, as part of the format string
containing a number after the decimal poiint.  So '%6.2f',
'%6.02f', and '%6.00002f' mean exactly the same thing, namely to
put 2 digits after the decimal point (and if that means padding
with zeroes, then so be it).

HTH,
Heather

-- 
Heather Coppersmith
That's not right; that's not even wrong. -- Wolfgang Pauli