From: redmine@...
Date: 2011-04-18T12:06:24+09:00
Subject: [ruby-core:35804] [Ruby 1.9 - Bug #4576] Range#step miss the last value, if end-exclusive and has float number


Issue #4576 has been updated by Tomoyuki Chikanaga.


test_step_ruby_core_35753 seems depend on platform.
On i686-linux it fails.

   1) Failure:
 test_step_ruby_core_35753(TestRange) [/home/chikanaga/opt/ruby-trunk/src/ruby/test/ruby/test_range.rb:190]:
 <3> expected but was
 <4>.

Rebuild with "cflags=-ffloat-store" option fixes this failure. It seems a "learn floating point number" issue.
May i partially revert an testcase of test_step_ruby_core_35753?
----------------------------------------
Bug #4576: Range#step miss the last value, if end-exclusive and has float number
http://redmine.ruby-lang.org/issues/4576

Author: Joey Zhou
Status: Closed
Priority: Normal
Assignee: 
Category: 
Target version: 
ruby -v: ruby 1.9.2p180 (2011-02-18) [i386-mingw32]


Hi, I find that:

* if: range.exclude_end? == true
* and: any one in [begin_obj, end_obj, step] is a true Float(f.to_i != f)
* and: unless begin_obj + step*int == end_obj
* then: the result will miss the last value.

for example:

 p (1...6.3).step.to_a # => [1.0, 2.0, 3.0, 4.0, 5.0], no 6.0
 p (1.1...6).step.to_a # => [1.1, 2.1, 3.1, 4.1], no 5.1
 p (1...6).step(1.1).to_a # => [1.0, 2.1, 3.2, 4.300000000000001], no 5.4

 p (1.0...6.6).step(1.9).to_a # => [1.0, 2.9], no 4.8
 p (1.0...6.7).step(1.9).to_a # => [1.0, 2.9, 4.8]
 p (1.0...6.8).step(1.9).to_a # => [1.0, 2.9, 4.8], no 6.7

Maybe the #step is ok on integers, but there's something wrong if the range is end-exclusive and contain float numbers.


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