Bugs item #1153226, was opened at 2005-02-28 05:10
Message generated for change (Comment added) made by arigo
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Category: Python Interpreter Core
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Stephen Thorne (jerub)
Assigned to: Nobody/Anonymous (nobody)
Summary: string interpolation breaks with %d and large float
Initial Comment:
We have experienced a problem recently when wanting to
render a large float as a string. Converting the float
to an int/long manuall was required.
'%d' % f
throws an exception for all floats f, f >= 2**31
Expected output, shown with 'int()' and 'long()':
>>> '%d %d' % (long(float(2**31)), int(float(2**31)))
'2147483648 2147483648'
Non-Working Example.
>>> '%d' % float(2**31)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: int argument required
Tested on:
Python 2.3.4 (#1, Oct 26 2004, 16:42:40)
Python 2.4.1a0 (#2, Feb 9 2005, 22:42:24)
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>Comment By: Armin Rigo (arigo)
Date: 2005-03-17 12:21
Message:
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I am afraid that the same problem occurs all over the place, wherever long
integers are accepted by built-in operations or functions. Most of these
places accept (and round) a float argument as well, though this is supposedly
deprecated. For example:
f = open('filename')
f.seek(999999999999) # ok
f.seek(12.0) # ok
f.seek(999999999999.0) # OverflowError
Unless someone is willing to conduct a systematic review I believe it unlikely
that it will get fixed, given the deprecation status.
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Comment By: Skip Montanaro (montanaro)
Date: 2005-03-02 00:42
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Sorry, I got corn-fused and misinterpreted 2**50 as 2e50.
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Comment By: Stephen Thorne (jerub)
Date: 2005-03-01 23:53
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%ld doesn't help. see the following example:
>>> "%.f" % float(2**31)
'2147483648'
>>> "%ld" % float(2**31)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: int argument required
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Comment By: Skip Montanaro (montanaro)
Date: 2005-03-01 15:38
Message:
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This is probably a corner case that got missed in the
int/long convergence. Still, is there a reason not to use
%.f when you know you are passing a float and want to
display it with no fractional component?
>>> '%.f' % 2**50
'1125899906842624'
or %ld if you expect the range to exceed the integer limits of
your hardware?
>>> '%ld' % 2**50
'1125899906842624'
I agree the documentation could probably be improved
in this area.
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Comment By: Stephen Thorne (jerub)
Date: 2005-03-01 13:21
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My immediate reaction is, yes. This is a bug.
Either floats should work with %d, or they should not at
all. Having a platform dependant upper bound on the size of
the float allowed is a bug.
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Comment By: Josiah Carlson (josiahcarlson)
Date: 2005-03-01 06:36
Message:
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Note that it will also raise a TypeError when the float f, f
< -2**31
Is this a bug? I don't know. I tend to not pass floats
when string interpolation is expecting integers. Maybe the
documentation should be cleared up.
If you really want a truncated float, perhaps "%.0f" is the
format you are looking for, to save you the effort of using
int() or long().
----------------------------------------------------------------------
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