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| partizan |
 Posted: Sun Jan 10, 2010 5:12 pm |
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Joined: 07 Sep 2009
Posts: 2
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Release: R13B03
Steps to reproduce:
1) erlang:list_to_float("42")
Expected result:
42.0 (float)
Actual result:
error:badarg
--
With best regards,
Alexander Borovsky
________________________________________________________________
erlang-bugs mailing list. See http://www.erlang.org/faq.html
erlang-bugs (at) erlang.org
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| uwiger |
| Posted: Sun Jan 10, 2010 5:58 pm |
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Joined: 03 Jul 2006
Posts: 604
Location: Sweden
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Alexander Borovsky wrote:
> Release: R13B03
>
> Steps to reproduce:
> 1) erlang:list_to_float("42")
>
> Expected result:
> 42.0 (float)
>
> Actual result:
> error:badarg
Arguably, this is in line with the documented behaviour:
"list_to_float(String) -> float()
Types:
String = string()
Returns the float whose text representation is String.
> list_to_float("2.2017764e+0").
2.2017764
Failure: badarg if String contains a bad representation of a float."
There is no float that has the text representation "42".
Eshell V5.7.2 (abort with ^G)
1> is_float(42).
false
BR,
Ulf W
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| partizan |
| Posted: Sun Jan 10, 2010 6:53 pm |
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Joined: 07 Sep 2009
Posts: 2
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On Sun, Jan 10, 2010 at 19:58, Ulf Wiger wrote:
> Alexander Borovsky wrote:
>> Release: R13B03
>>
>> Steps to reproduce:
>> 1) erlang:list_to_float("42")
>>
>> Expected result:
>> 42.0 (float)
>>
>> Actual result:
>> error:badarg
>
> Arguably, this is in line with the documented behaviour:
>
> "list_to_float(String) -> float()
>
> Types:
> String = string()
>
> Returns the float whose text representation is String.
>
>> list_to_float("2.2017764e+0").
> 2.2017764
>
> Failure: badarg if String contains a bad representation of a float."
>
>
> There is no float that has the text representation "42".
42.0 could have text representation "42".
In most languages (C, Java, Ruby, etc) "42" parsed to float with no errors.
Also in some cases float values could be outputted with no decimal point:
In C:
#include<stdio.h>
int main() {
double d = 42;
printf("%g\n", d);
return 0;
}
will print "42"
So integers should be properly parsed by list_to_float() function (as
corresponding float value)
--
With best regards,
Alexander Borovsky
________________________________________________________________
erlang-bugs mailing list. See http://www.erlang.org/faq.html
erlang-bugs (at) erlang.org
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| FredrikSvahn |
| Posted: Sun Jan 10, 2010 7:29 pm |
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Joined: 19 Jun 2007
Posts: 31
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See: http://old.nabble.com/list_to_float%28%29-td19309221.html
BR /Fredrik
On Sun, Jan 10, 2010 at 7:53 PM, Alexander Borovsky
<alex.borovsky@gmail.com> wrote:
> On Sun, Jan 10, 2010 at 19:58, Ulf Wiger wrote:
>
>> Alexander Borovsky wrote:
>>> Release: R13B03
>>>
>>> Steps to reproduce:
>>> 1) erlang:list_to_float("42")
>>>
>>> Expected result:
>>> 42.0 (float)
>>>
>>> Actual result:
>>> error:badarg
>>
>> Arguably, this is in line with the documented behaviour:
>>
>> "list_to_float(String) -> float()
>>
>> Types:
>> String = string()
>>
>> Returns the float whose text representation is String.
>>
>>> list_to_float("2.2017764e+0").
>> 2.2017764
>>
>> Failure: badarg if String contains a bad representation of a float."
>>
>>
>> There is no float that has the text representation "42".
>
> 42.0 could have text representation "42".
>
> In most languages (C, Java, Ruby, etc) "42" parsed to float with no errors.
>
> Also in some cases float values could be outputted with no decimal point:
>
> In C:
> #include<stdio.h>
>
> int main() {
> |
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| uwiger |
| Posted: Sun Jan 10, 2010 7:31 pm |
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User
Joined: 03 Jul 2006
Posts: 604
Location: Sweden
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-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1
Alexander Borovsky wrote:
>
> 42.0 could have text representation "42".
>
> In most languages (C, Java, Ruby, etc) "42" parsed to float with no errors.
>
> Also in some cases float values could be outputted with no decimal point:
This is why I wrote "arguably". 
The question has been up on the mailing list before:
http://www.erlang.org/cgi-bin/ezmlm-cgi?4:msp:15372:bkelgefglpkakhbedlbf
(May 12 2005)
http://www.erlang.org/cgi-bin/ezmlm-cgi/4/27647 (Jul 3 2007)
http://www.erlang.org/cgi-bin/ezmlm-cgi/4/37899 (Sep 4 2008)
In the last one, Richard Carlsson wrote:
It's a "feature": list_to_float/1 is a rather low level function,
which assumes that you have already checked that the string has the
proper form for an Erlang float, i.e., "0.0" and "1.0E-3" are ok,
but "22", ".0", and "0." are not.
But you're definitely not the first one to disagree with this design
decision.
BR,
UlfW
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WE'VE CHANGED NAMES!
Since January 1st 2010 Erlang Training and Consulting Ltd. has become ERLANG SOLUTIONS LTD.
www.erlang-solutions.com
________________________________________________________________
erlang-bugs mailing list. See http://www.erlang.org/faq.html
erlang-bugs (at) erlang.org
---------------------------------------------------
---------------------------------------------------
WE'VE CHANGED NAMES!
Since January 1st 2010 Erlang Training and Consulting Ltd. has become ERLANG SOLUTIONS LTD.
www.erlang-solutions.com
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| rvirding |
| Posted: Mon Jan 11, 2010 6:35 pm |
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User
Joined: 30 Aug 2006
Posts: 452
Location: Stockholm, Sweden
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2010/1/10 Ulf Wiger <ulf.wiger@erlang-consulting.com>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Alexander Borovsky wrote:
> >
> > 42.0 could have text representation "42".
> >
> > In most languages (C, Java, Ruby, etc) "42" parsed to float with no
> errors.
> >
> > Also in some cases float values could be outputted with no decimal point:
>
> This is why I wrote "arguably".
>
> The question has been up on the mailing list before:
>
> http://www.erlang.org/cgi-bin/ezmlm-cgi?4:msp:15372:bkelgefglpkakhbedlbf
> (May 12 2005)
> http://www.erlang.org/cgi-bin/ezmlm-cgi/4/27647 (Jul 3 2007)
> http://www.erlang.org/cgi-bin/ezmlm-cgi/4/37899 (Sep 4 2008)
>
> In the last one, Richard Carlsson wrote:
>
> It's a "feature": list_to_float/1 is a rather low level function,
> which assumes that you have already checked that the string has the
> proper form for an Erlang float, i.e., "0.0" and "1.0E-3" are ok,
> but "22", ".0", and "0." are not.
>
> But you're definitely not the first one to disagree with this design
> decision.
>
I *knew* it was a mistake to add floats in the first place. If NASA can hit
the moon without them why should we need them for a telephone exchange or
serving up a few pages on the web?
Robert
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| Guest |
| Posted: Wed Jan 13, 2010 1:20 am |
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Wings3D?
On Mon, Jan 11, 2010 at 12:34 PM, Robert Virding <rvirding@gmail.com> wrote:
> 2010/1/10 Ulf Wiger <ulf.wiger@erlang-consulting.com>
>
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > Alexander Borovsky wrote:
> > >
> > > 42.0 could have text representation "42".
> > >
> > > In most languages (C, Java, Ruby, etc) "42" parsed to float with no
> > errors.
> > >
> > > Also in some cases float values could be outputted with no decimal
> point:
> >
> > This is why I wrote "arguably".
> >
> > The question has been up on the mailing list before:
> >
> > http://www.erlang.org/cgi-bin/ezmlm-cgi?4:msp:15372:bkelgefglpkakhbedlbf
> > (May 12 2005)
> > http://www.erlang.org/cgi-bin/ezmlm-cgi/4/27647 (Jul 3 2007)
> > http://www.erlang.org/cgi-bin/ezmlm-cgi/4/37899 (Sep 4 2008)
> >
> > In the last one, Richard Carlsson wrote:
> >
> > It's a "feature": list_to_float/1 is a rather low level function,
> > which assumes that you have already checked that the string has the
> > proper form for an Erlang float, i.e., "0.0" and "1.0E-3" are ok,
> > but "22", ".0", and "0." are not.
> >
> > But you're definitely not the first one to disagree with this design
> > decision.
> >
>
> I *knew* it was a mistake to add floats in the first place. If NASA can hit
> the moon without them why should we need them for a telephone exchange or
> serving up a few pages on the web?
>
> Robert
>
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