From: Rajinder Yadav <devguy.ca@...>
Date: 2009-12-22T22:36:20+09:00
Subject: Re: integers and floats

Paul Smith wrote:
> On Tue, Dec 22, 2009 at 1:01 PM, Rajinder Yadav <devguy.ca@gmail.com> wrote:
>> Can someone explain to me why Ruby treats integers and floating point
>> numbers differently?
>>
>> irb(main):069:0> 12.equal? 12
>> => true
>>
>> irb(main):071:0> 12.0.equal? 12.0
>> => false
> 
> Because they're different :)

thanks, I understand the object_id

my question is why is 12.0 constructed each time and 12 is immediate? 
does it have to do with the fact that floats are simply binary 
approximation.

> 
> With .equal you're checking to see whether 2 objects are in fact the
> same object.  12, a Fixnum, is an immediate object, meaning all the
> 12s in your code are in fact the exact same object.
> 
> 12.0, a floating point number, is constructed from scratch each time
> you refer to it.  So the 12.0 on the left is a separate construction
> from the the 12.0 on the right.
> 
> irb(main):008:0> 12.object_id
> => 25
> irb(main):009:0> a = 12
> => 12
> irb(main):010:0> b = 12
> => 12
> irb(main):011:0> a.object_id
> => 25
> irb(main):012:0> b.object_id
> => 25
> 
> All of these 12's are the same object.
> 
> irb(main):013:0> 12.0.object_id
> => 11121408
> irb(main):014:0> a = 12.0
> => 12.0
> irb(main):015:0> b = 12.0
> => 12.0
> irb(main):016:0> a.object_id
> => 11187424
> irb(main):017:0> b.object_id
> => 10954912
> 
> All of these 12.0s are different objects
> 
> irb(main):018:0> 12 == 12
> => true
> irb(main):019:0> 12.0 == 12.0
> => true
> 
> But all of the 12.0s have the same value.
> 
> The same distinction happens for symbols and strings:
> 
> irb(main):020:0> "abc".equal? "abc"
> => false
> irb(main):021:0> :abc.equal? :abc
> => true
> 
>> --
>> Kind Regards,
>> Rajinder Yadav
>>
>> http://DevMentor.org
>>
>> Do Good! - Share Freely
>>
>>
> 
> 
> 


-- 
Kind Regards,
Rajinder Yadav

http://DevMentor.org

Do Good! - Share Freely