[issue13433] String format documentation contains error regarding %g

[Christian Iversen]

New submission from Christian Iversen <ci at sikkerhed.org>:

The documentation for string format options state that both %f, %g and %e default to 6 digits after the decimal point. In fact, %g always seems to use 5 digits by default:

>>> "%g" % 2.1234567
'2.12346'
>>> "%f" % 2.1234567
'2.123457'
>>> "%e" % 2.1234567
'2.123457e+00'

But something much more insidious is wrong, because even when explicitly told how many digits to have, %g is one off:

>>> "%.6g" % 2.1234567
'2.12346'
>>> "%.6f" % 2.1234567
'2.123457'
>>> "%.6e" % 2.1234567
'2.123457e+00'

This can't be right?

----------
assignee: docs at python
components: Documentation
messages: 147940
nosy: Christian.Iversen, docs at python
priority: normal
severity: normal
status: open
title: String format documentation contains error regarding %g
type: behavior
versions: Python 2.6, Python 2.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue13433>
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