[Python-Dev] Float formatting and #

Georg Brandl g.brandl at gmx.net
Fri Apr 28 21:36:49 CEST 2006


Georg Brandl wrote:
> Is there a reason why the "alternate format" isn't documented for float
> conversions in http://docs.python.org/lib/typesseq-strings.html ?
> 
> '%#8.f' % 1.0 keeps the decimal point while '%8.f' % 1.0 drops it.
> 
> Also, for %g the alternate form keeps trailing zeroes.
> 
> While at it, I noticed a difference between %f and %g:
> 
> '%.3f' % 1.123 is "1.123" while
> '%.3g' % 1.123 is "1.12".
> 
> Is that intentional?

Reviewing the printf man page, this is okay since for %f, the precision is the
number of digits after the decimal point while for %g, it is the number of
significant digits. Still, that should be documented in the Python manual.

Georg



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