# Newbee Question on what if x === 2..5 does

**URL:** <https://rubytalk.org/t/newbee-question-on-what-if-x-2-5-does/27147>\
**Category:** ruby-talk\
**Created:** [3 May 2006 22:49 UTC](https://rubytalk.org/t/newbee-question-on-what-if-x-2-5-does/27147 "2006-05-03T22:49:15Z")\
**Posts on this page:** 8\
**Page:** 1

<div class="post-metadata">

**Author:** ![Rob\_Burrowes](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Rob\_Burrowes](https://rubytalk.org/u/Rob_Burrowes)\
**Post date:** [3 May 2006 22:49 UTC](https://rubytalk.org/t/newbee-question-on-what-if-x-2-5-does/27147/1 "2006-05-03T22:49:15Z")

</div>

I'm new to ruby and don't understand why the following code does what is does. Can anyone enlighten me?

ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| if (x === 2..5 ) then print x, " " end}; puts '  
2 3 4 5 6 7 8 9 10

I would have thought this would be the same as

ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| case x; when 2..5 then print x, " "; end}; puts '  
2 3 4 5

I am also confused that

ruby -e 'while gets; print if /\<div id=.\*$/ .. /\<\/body\>/; end' \< fred  
\<div id="eutpuhe"\>  
UETHUEPUK  
THEUTEUH  
teuhepxn  
thueonhoe  
ononueuouh  
\</div\>  
\</body\>

and a three . range test give the same output.

ruby -e 'while gets; print if /\<div id=.\*$/ ... /\<\/body\>/; end' \< fred  
\<div id="eutpuhe"\>  
UETHUEPUK  
THEUTEUH  
teuhepxn  
thueonhoe  
ononueuouh  
\</div\>  
\</body\>

The original file 'fred' is

\<html\>  
\<title\>hello\</title\>  
\<body\>  
\<div id="eutpuhe"\>  
UETHUEPUK  
THEUTEUH  
teuhepxn  
thueonhoe  
ononueuouh  
\</div\>  
\</body\>  
\</html\>

ruby -v  
ruby 1.8.4 (2005-12-24) [powerpc-darwin8.6.0]

Compiled from the distribution, not the Mac OS shipped version.

Rob

Rob Burrowes Ph: +64 (9) 3737 599 Extn 87972  
Computing Services Manager Fax: +64 (9) 3737 453  
Computer Science Department Mob:+64 (27) 4731 856  
The University of Auckland  
Rm 391, Level 3  
38 Princes Street [http://www.cs.auckland.ac.nz/~rob](http://www.cs.auckland.ac.nz/~rob)  
Private bag 92019 [http://www.wikarekare.org](http://www.wikarekare.org)  
Auckland 1001 [http://www.burrowes.org](http://www.burrowes.org)

---

<div class="post-metadata">

**Author:** ![Jacob\_Fugal](https://avatars.discourse-cdn.com/v4/letter/j/439d5e/32.png) [@Jacob\_Fugal](https://rubytalk.org/u/Jacob_Fugal)\
**Post date:** [3 May 2006 23:06 UTC](https://rubytalk.org/t/newbee-question-on-what-if-x-2-5-does/27147/2 "2006-05-03T23:06:47Z")

</div>

> I'm new to ruby and don't understand why the following code does what  
> is does. Can anyone enlighten me?
> 
> ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| if (x === 2..5 )  
> then print x, " " end}; puts '  
> 2 3 4 5 6 7 8 9 10
> 
> I would have thought this would be the same as
> 
> ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| case x; when 2..5  
> then print x, " "; end}; puts '  
> 2 3 4 5

Try switching x === 2..5 to 2..5 === x. The case equality operator  
(===) is not cummutative. The conditions of a case statement are  
evaluated using the when condition as the \*receiver\* of the case  
equality operator, not the argument. Ie.

&nbsp;&nbsp;case a  
&nbsp;&nbsp;when b  
&nbsp;&nbsp;&nbsp;&nbsp;...  
&nbsp;&nbsp;end

is equivalent to:

&nbsp;&nbsp;if b === a  
&nbsp;&nbsp;&nbsp;&nbsp;...  
&nbsp;&nbsp;end

> I am also confused that
> 
> ruby -e 'while gets; print if /\<div id=.\*$/ .. /\<\/body\>/; end' \< fred  
> \<div id="eutpuhe"\>  
> UETHUEPUK  
> THEUTEUH  
> teuhepxn  
> thueonhoe  
> ononueuouh  
> \</div\>  
> \</body\>
> 
> and a three . range test give the same output.
> 
> ruby -e 'while gets; print if /\<div id=.\*$/ ... /\<\/body\>/; end' \< fred  
> \<div id="eutpuhe"\>  
> UETHUEPUK  
> THEUTEUH  
> teuhepxn  
> thueonhoe  
> ononueuouh  
> \</div\>  
> \</body\>

Sorry, can't help you there. I always have a hard time remembering  
what the difference between .. and ... are in that context. I stay  
away from it in favor of more descriptive flagging in a while loop.  
E.g.:

&nbsp;&nbsp;flag = false  
&nbsp;&nbsp;while line = gets  
&nbsp;&nbsp;&nbsp;&nbsp;flag = true if line =~ /\<div id=.\*$/  
&nbsp;&nbsp;&nbsp;&nbsp;flag = false if line =~ /\<\/body\>/  
&nbsp;&nbsp;&nbsp;&nbsp;print line if flag  
&nbsp;&nbsp;end

Jacob Fugal

> **···**
>
> On 5/3/06, Rob Burrowes \<rob@cs.auckland.ac.nz\> wrote:

---

<div class="post-metadata">

**Author:** ![Rob\_Burrowes](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Rob\_Burrowes](https://rubytalk.org/u/Rob_Burrowes)\
**Post date:** [4 May 2006 00:42 UTC](https://rubytalk.org/t/newbee-question-on-what-if-x-2-5-does/27147/3 "2006-05-04T00:42:45Z")

</div>

I get what you mean. It makes sense to have the === as a method of the range, not of x, but this produces no result at all.

rob1:~ rbur004$ ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| print x, "-\>"; if (2...5 == x) then print x, " " end; print "\n"}'  
1-\>  
2-\>  
3-\>  
4-\>  
5-\>  
6-\>  
7-\>  
8-\>  
9-\>  
10-\>

> > I'm new to ruby and don't understand why the following code does what  
> > is does. Can anyone enlighten me?
> > 
> > ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| if (x === 2..5 )  
> > then print x, " " end}; puts '  
> > 2 3 4 5 6 7 8 9 10
> > 
> > I would have thought this would be the same as
> > 
> > ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| case x; when 2..5  
> > then print x, " "; end}; puts '  
> > 2 3 4 5
> 
> Try switching x === 2..5 to 2..5 === x. The case equality operator  
> (===) is not cummutative. The conditions of a case statement are  
> evaluated using the when condition as the \*receiver\* of the case  
> equality operator, not the argument. Ie.
> 
> case a  
> when b  
> &nbsp;&nbsp;&nbsp;...  
> end
> 
> is equivalent to:
> 
> if b === a  
> &nbsp;&nbsp;&nbsp;...  
> end
> 
> > I am also confused that
> > 
> > ruby -e 'while gets; print if /\<div id=.\*$/ .. /\<\/body\>/; end' \< fred  
> > \<div id="eutpuhe"\>  
> > UETHUEPUK  
> > THEUTEUH  
> > teuhepxn  
> > thueonhoe  
> > ononueuouh  
> > \</div\>  
> > \</body\>
> > 
> > and a three . range test give the same output.
> > 
> > ruby -e 'while gets; print if /\<div id=.\*$/ ... /\<\/body\>/; end' \< fred  
> > \<div id="eutpuhe"\>  
> > UETHUEPUK  
> > THEUTEUH  
> > teuhepxn  
> > thueonhoe  
> > ononueuouh  
> > \</div\>  
> > \</body\>
> 
> Sorry, can't help you there. I always have a hard time remembering  
> what the difference between .. and ... are in that context. I stay  
> away from it in favor of more descriptive flagging in a while loop.  
> E.g.:
> 
> flag = false  
> while line = gets  
> &nbsp;&nbsp;&nbsp;flag = true if line =~ /\<div id=.\*$/  
> &nbsp;&nbsp;&nbsp;flag = false if line =~ /\<\/body\>/  
> &nbsp;&nbsp;&nbsp;print line if flag  
> end
> 
> Jacob Fugal

Rob

Rob Burrowes Ph: +64 (9) 3737 599 Extn 87972  
Computing Services Manager Fax: +64 (9) 3737 453  
Computer Science Department Mob:+64 (27) 4731 856  
The University of Auckland  
Rm 391, Level 3  
38 Princes Street [http://www.cs.auckland.ac.nz/~rob](http://www.cs.auckland.ac.nz/~rob)  
Private bag 92019 [http://www.wikarekare.org](http://www.wikarekare.org)  
Auckland 1001 [http://www.burrowes.org](http://www.burrowes.org)

> **···**
>
> On 4/05/2006, at 11:06 AM, Jacob Fugal wrote:
> 
> > On 5/3/06, Rob Burrowes \<rob@cs.auckland.ac.nz\> wrote:

---

<div class="post-metadata">

**Author:** ![Rob\_Burrowes](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Rob\_Burrowes](https://rubytalk.org/u/Rob_Burrowes)\
**Post date:** [4 May 2006 01:00 UTC](https://rubytalk.org/t/newbee-question-on-what-if-x-2-5-does/27147/4 "2006-05-04T01:00:21Z")

</div>

I mistyped that (left out an =), but the same result.

rob1:~ rbur004$ ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| print x, "-\>"; if (2...5 === x) then print x, " " end; print "\n"}'  
1-\>  
2-\>  
3-\>  
4-\>  
5-\>  
6-\>  
7-\>  
8-\>  
9-\>  
10-\>

> I get what you mean. It makes sense to have the === as a method of the range, not of x, but this produces no result at all.
> 
> rob1:~ rbur004$ ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| print x, "-\>"; if (2...5 == x) then print x, " " end; print "\n"}'  
> 1-\>  
> 2-\>  
> 3-\>  
> 4-\>  
> 5-\>  
> 6-\>  
> 7-\>  
> 8-\>  
> 9-\>  
> 10-\>
> 
> > > I'm new to ruby and don't understand why the following code does what  
> > > is does. Can anyone enlighten me?
> > > 
> > > ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| if (x === 2..5 )  
> > > then print x, " " end}; puts '  
> > > 2 3 4 5 6 7 8 9 10
> > > 
> > > I would have thought this would be the same as
> > > 
> > > ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| case x; when 2..5  
> > > then print x, " "; end}; puts '  
> > > 2 3 4 5
> > 
> > Try switching x === 2..5 to 2..5 === x. The case equality operator  
> > (===) is not cummutative. The conditions of a case statement are  
> > evaluated using the when condition as the \*receiver\* of the case  
> > equality operator, not the argument. Ie.
> > 
> > case a  
> > when b  
> > &nbsp;&nbsp;&nbsp;...  
> > end
> > 
> > is equivalent to:
> > 
> > if b === a  
> > &nbsp;&nbsp;&nbsp;...  
> > end
> > 
> > > I am also confused that
> > > 
> > > ruby -e 'while gets; print if /\<div id=.\*$/ .. /\<\/body\>/; end' \< fred  
> > > \<div id="eutpuhe"\>  
> > > UETHUEPUK  
> > > THEUTEUH  
> > > teuhepxn  
> > > thueonhoe  
> > > ononueuouh  
> > > \</div\>  
> > > \</body\>
> > > 
> > > and a three . range test give the same output.
> > > 
> > > ruby -e 'while gets; print if /\<div id=.\*$/ ... /\<\/body\>/; end' \< fred  
> > > \<div id="eutpuhe"\>  
> > > UETHUEPUK  
> > > THEUTEUH  
> > > teuhepxn  
> > > thueonhoe  
> > > ononueuouh  
> > > \</div\>  
> > > \</body\>
> > 
> > Sorry, can't help you there. I always have a hard time remembering  
> > what the difference between .. and ... are in that context. I stay  
> > away from it in favor of more descriptive flagging in a while loop.  
> > E.g.:
> > 
> > flag = false  
> > while line = gets  
> > &nbsp;&nbsp;&nbsp;flag = true if line =~ /\<div id=.\*$/  
> > &nbsp;&nbsp;&nbsp;flag = false if line =~ /\<\/body\>/  
> > &nbsp;&nbsp;&nbsp;print line if flag  
> > end
> > 
> > Jacob Fugal
> 
> Rob
> 
> Rob Burrowes Ph: +64 (9) 3737 599 Extn 87972  
> Computing Services Manager Fax: +64 (9) 3737 453  
> Computer Science Department Mob:+64 (27) 4731 856  
> The University of Auckland  
> Rm 391, Level 3  
> 38 Princes Street [http://www.cs.auckland.ac.nz/~rob](http://www.cs.auckland.ac.nz/~rob)  
> Private bag 92019 [http://www.wikarekare.org](http://www.wikarekare.org)  
> Auckland 1001 [http://www.burrowes.org](http://www.burrowes.org)

Rob

Rob Burrowes Ph: +64 (9) 3737 599 Extn 87972  
Computing Services Manager Fax: +64 (9) 3737 453  
Computer Science Department Mob:+64 (27) 4731 856  
The University of Auckland  
Rm 391, Level 3  
38 Princes Street [http://www.cs.auckland.ac.nz/~rob](http://www.cs.auckland.ac.nz/~rob)  
Private bag 92019 [http://www.wikarekare.org](http://www.wikarekare.org)  
Auckland 1001 [http://www.burrowes.org](http://www.burrowes.org)

> **···**
>
> On 4/05/2006, at 12:42 PM, Rob Burrowes wrote:
> 
> > On 4/05/2006, at 11:06 AM, Jacob Fugal wrote:
> > 
> > > On 5/3/06, Rob Burrowes \<rob@cs.auckland.ac.nz\> wrote:

---

<div class="post-metadata">

**Author:** ![Rob\_Burrowes](https://avatars.discourse-cdn.com/v4/letter/r/779978/32.png) [@Rob\_Burrowes](https://rubytalk.org/u/Rob_Burrowes)\
**Post date:** [4 May 2006 01:13 UTC](https://rubytalk.org/t/newbee-question-on-what-if-x-2-5-does/27147/5 "2006-05-04T01:13:01Z")

</div>

Hmmm, it works if I bracket the range. Why is that?

rob1:~ rbur004$ ruby -e '[1,2,3,4,5,6,7,8,9,10].each { |x| print x, "- \>"; if ((2...5) === x) then print x end; print "\n"}'  
1-\>  
2-\>2  
3-\>3  
4-\>4  
5-\>  
6-\>  
7-\>  
8-\>  
9-\>  
10-\>

> I mistyped that (left out an =), but the same result.
> 
> rob1:~ rbur004$ ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| print x, "-\>"; if (2...5 === x) then print x, " " end; print "\n"}'  
> 1-\>  
> 2-\>  
> 3-\>  
> 4-\>  
> 5-\>  
> 6-\>  
> 7-\>  
> 8-\>  
> 9-\>  
> 10-\>
> 
> > I get what you mean. It makes sense to have the === as a method of the range, not of x, but this produces no result at all.
> > 
> > rob1:~ rbur004$ ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| print x, "-\>"; if (2...5 == x) then print x, " " end; print "\n"}'  
> > 1-\>  
> > 2-\>  
> > 3-\>  
> > 4-\>  
> > 5-\>  
> > 6-\>  
> > 7-\>  
> > 8-\>  
> > 9-\>  
> > 10-\>
> > 
> > > > I'm new to ruby and don't understand why the following code does what  
> > > > is does. Can anyone enlighten me?
> > > > 
> > > > ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| if (x === 2..5 )  
> > > > then print x, " " end}; puts '  
> > > > 2 3 4 5 6 7 8 9 10
> > > > 
> > > > I would have thought this would be the same as
> > > > 
> > > > ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| case x; when 2..5  
> > > > then print x, " "; end}; puts '  
> > > > 2 3 4 5
> > > 
> > > Try switching x === 2..5 to 2..5 === x. The case equality operator  
> > > (===) is not cummutative. The conditions of a case statement are  
> > > evaluated using the when condition as the \*receiver\* of the case  
> > > equality operator, not the argument. Ie.
> > > 
> > > case a  
> > > when b  
> > > &nbsp;&nbsp;&nbsp;...  
> > > end
> > > 
> > > is equivalent to:
> > > 
> > > if b === a  
> > > &nbsp;&nbsp;&nbsp;...  
> > > end
> > > 
> > > > I am also confused that
> > > > 
> > > > ruby -e 'while gets; print if /\<div id=.\*$/ .. /\<\/body\>/; end' \< fred  
> > > > \<div id="eutpuhe"\>  
> > > > UETHUEPUK  
> > > > THEUTEUH  
> > > > teuhepxn  
> > > > thueonhoe  
> > > > ononueuouh  
> > > > \</div\>  
> > > > \</body\>
> > > > 
> > > > and a three . range test give the same output.
> > > > 
> > > > ruby -e 'while gets; print if /\<div id=.\*$/ ... /\<\/body\>/; end' \< fred  
> > > > \<div id="eutpuhe"\>  
> > > > UETHUEPUK  
> > > > THEUTEUH  
> > > > teuhepxn  
> > > > thueonhoe  
> > > > ononueuouh  
> > > > \</div\>  
> > > > \</body\>
> > > 
> > > Sorry, can't help you there. I always have a hard time remembering  
> > > what the difference between .. and ... are in that context. I stay  
> > > away from it in favor of more descriptive flagging in a while loop.  
> > > E.g.:
> > > 
> > > flag = false  
> > > while line = gets  
> > > &nbsp;&nbsp;&nbsp;flag = true if line =~ /\<div id=.\*$/  
> > > &nbsp;&nbsp;&nbsp;flag = false if line =~ /\<\/body\>/  
> > > &nbsp;&nbsp;&nbsp;print line if flag  
> > > end
> > > 
> > > Jacob Fugal
> > 
> > Rob
> > 
> > Rob Burrowes Ph: +64 (9) 3737 599 Extn 87972  
> > Computing Services Manager Fax: +64 (9) 3737 453  
> > Computer Science Department Mob:+64 (27) 4731 856  
> > The University of Auckland  
> > Rm 391, Level 3  
> > 38 Princes Street [Robs Home Page](http://www.cs.auckland.ac.nz/~rob)  
> > Private bag 92019 [http://www.wikarekare.org](http://www.wikarekare.org)  
> > Auckland 1001 [http://www.burrowes.org](http://www.burrowes.org)
> 
> Rob
> 
> Rob Burrowes Ph: +64 (9) 3737 599 Extn 87972  
> Computing Services Manager Fax: +64 (9) 3737 453  
> Computer Science Department Mob:+64 (27) 4731 856  
> The University of Auckland  
> Rm 391, Level 3  
> 38 Princes Street [Robs Home Page](http://www.cs.auckland.ac.nz/~rob)  
> Private bag 92019 [http://www.wikarekare.org](http://www.wikarekare.org)  
> Auckland 1001 [http://www.burrowes.org](http://www.burrowes.org)

Rob

Rob Burrowes Ph: +64 (9) 3737 599 Extn 87972  
Computing Services Manager Fax: +64 (9) 3737 453  
Computer Science Department Mob:+64 (27) 4731 856  
The University of Auckland  
Rm 391, Level 3  
38 Princes Street [Robs Home Page](http://www.cs.auckland.ac.nz/~rob)  
Private bag 92019 [http://www.wikarekare.org](http://www.wikarekare.org)  
Auckland 1001 [http://www.burrowes.org](http://www.burrowes.org)

> **···**
>
> On 4/05/2006, at 1:00 PM, Rob Burrowes wrote:
> 
> > On 4/05/2006, at 12:42 PM, Rob Burrowes wrote:
> > 
> > > On 4/05/2006, at 11:06 AM, Jacob Fugal wrote:
> > > 
> > > > On 5/3/06, Rob Burrowes \<rob@cs.auckland.ac.nz\> wrote:

---

<div class="post-metadata">

**Author:** ![Daniel\_Baird](https://avatars.discourse-cdn.com/v4/letter/d/df788c/32.png) [@Daniel\_Baird](https://rubytalk.org/u/Daniel_Baird)\
**Post date:** [4 May 2006 01:17 UTC](https://rubytalk.org/t/newbee-question-on-what-if-x-2-5-does/27147/6 "2006-05-04T01:17:00Z")

</div>

Try using:  
&nbsp;&nbsp;if (2...5) === x

the === seems to bind before the ...

;D

> **···**
>
> On 5/4/06, Rob Burrowes \<rob@cs.auckland.ac.nz\> wrote:
> 
> > I mistyped that (left out an =), but the same result.
> > 
> > rob1:~ rbur004$ ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x|  
> > print x, "-\>"; if (2...5 === x) then print x, " " end; print "\n"}'  
> > 1-\>  
> > 2-\>  
> > 3-\>  
> > 4-\>  
> > 5-\>  
> > 6-\>  
> > 7-\>  
> > 8-\>  
> > 9-\>  
> > 10-\>
> > 
> > On 4/05/2006, at 12:42 PM, Rob Burrowes wrote:
> > 
> > \> I get what you mean. It makes sense to have the === as a method of  
> > \> the range, not of x, but this produces no result at all.  
> > \>  
> > \> rob1:~ rbur004$ ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x|  
> > \> print x, "-\>"; if (2...5 == x) then print x, " " end; print "\n"}'  
> > \> 1-\>  
> > \> 2-\>  
> > \> 3-\>  
> > \> 4-\>  
> > \> 5-\>  
> > \> 6-\>  
> > \> 7-\>  
> > \> 8-\>  
> > \> 9-\>  
> > \> 10-\>  
> > \>  
> > \> On 4/05/2006, at 11:06 AM, Jacob Fugal wrote:  
> > \>  
> > \>\> On 5/3/06, Rob Burrowes \<rob@cs.auckland.ac.nz\> wrote:  
> > \>\>\> I'm new to ruby and don't understand why the following code does  
> > \>\>\> what  
> > \>\>\> is does. Can anyone enlighten me?  
> > \>\>\>  
> > \>\>\> ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| if (x === 2..5 )  
> > \>\>\> then print x, " " end}; puts '  
> > \>\>\> 2 3 4 5 6 7 8 9 10  
> > \>\>\>  
> > \>\>\> I would have thought this would be the same as  
> > \>\>\>  
> > \>\>\> ruby -e 'a = [1,2,3,4,5,6,7,8,9,10]; a.each { |x| case x; when 2..5  
> > \>\>\> then print x, " "; end}; puts '  
> > \>\>\> 2 3 4 5  
> > \>\>  
> > \>\> Try switching x === 2..5 to 2..5 === x. The case equality operator  
> > \>\> (===) is not cummutative. The conditions of a case statement are  
> > \>\> evaluated using the when condition as the \*receiver\* of the case  
> > \>\> equality operator, not the argument. Ie.  
> > \>\>  
> > \>\> case a  
> > \>\> when b  
> > \>\> ...  
> > \>\> end  
> > \>\>  
> > \>\> is equivalent to:  
> > \>\>  
> > \>\> if b === a  
> > \>\> ...  
> > \>\> end  
> > \>\>  
> > \>\>\> I am also confused that  
> > \>\>\>  
> > \>\>\> ruby -e 'while gets; print if /\<div id=.\*$/ .. /\<\/body\>/; end'  
> > \>\>\> \< fred  
> > \>\>\> \<div id="eutpuhe"\>  
> > \>\>\> UETHUEPUK  
> > \>\>\> THEUTEUH  
> > \>\>\> teuhepxn  
> > \>\>\> thueonhoe  
> > \>\>\> ononueuouh  
> > \>\>\> \</div\>  
> > \>\>\> \</body\>  
> > \>\>\>  
> > \>\>\> and a three . range test give the same output.  
> > \>\>\>  
> > \>\>\> ruby -e 'while gets; print if /\<div id=.\*$/ ... /\<\/body\>/; end'  
> > \>\>\> \< fred  
> > \>\>\> \<div id="eutpuhe"\>  
> > \>\>\> UETHUEPUK  
> > \>\>\> THEUTEUH  
> > \>\>\> teuhepxn  
> > \>\>\> thueonhoe  
> > \>\>\> ononueuouh  
> > \>\>\> \</div\>  
> > \>\>\> \</body\>  
> > \>\>  
> > \>\> Sorry, can't help you there. I always have a hard time remembering  
> > \>\> what the difference between .. and ... are in that context. I stay  
> > \>\> away from it in favor of more descriptive flagging in a while loop.  
> > \>\> E.g.:  
> > \>\>  
> > \>\> flag = false  
> > \>\> while line = gets  
> > \>\> flag = true if line =~ /\<div id=.\*$/  
> > \>\> flag = false if line =~ /\<\/body\>/  
> > \>\> print line if flag  
> > \>\> end  
> > \>\>  
> > \>\> Jacob Fugal  
> > \>\>  
> > \>  
> > \> Rob  
> > \>  
> > \> Rob Burrowes Ph: +64 (9) 3737 599 Extn 87972  
> > \> Computing Services Manager Fax: +64 (9) 3737 453  
> > \> Computer Science Department Mob:+64 (27) 4731 856  
> > \> The University of Auckland  
> > \> Rm 391, Level 3  
> > \> 38 Princes Street [http://www.cs.auckland.ac.nz/~rob](http://www.cs.auckland.ac.nz/~rob)  
> > \> Private bag 92019 [http://www.wikarekare.org](http://www.wikarekare.org)  
> > \> Auckland 1001 [http://www.burrowes.org](http://www.burrowes.org)  
> > \>
> > 
> > Rob
> > 
> > Rob Burrowes Ph: +64 (9) 3737 599 Extn 87972  
> > Computing Services Manager Fax: +64 (9) 3737 453  
> > Computer Science Department Mob:+64 (27) 4731 856  
> > The University of Auckland  
> > Rm 391, Level 3  
> > 38 Princes Street [http://www.cs.auckland.ac.nz/~rob](http://www.cs.auckland.ac.nz/~rob)  
> > Private bag 92019 [http://www.wikarekare.org](http://www.wikarekare.org)  
> > Auckland 1001 [http://www.burrowes.org](http://www.burrowes.org)
> 
> --  
> Daniel Baird  
> [http://danielbaird.com](http://danielbaird.com) (TiddlyW;nks! :: Whiteboard Koala :: Blog :: Things  
> That Suck)

---

<div class="post-metadata">

**Author:** ![Logan\_Capaldo](https://avatars.discourse-cdn.com/v4/letter/l/7ea924/32.png) [@Logan\_Capaldo](https://rubytalk.org/u/Logan_Capaldo)\
**Post date:** [4 May 2006 01:19 UTC](https://rubytalk.org/t/newbee-question-on-what-if-x-2-5-does/27147/7 "2006-05-04T01:19:22Z")

</div>

=== has higher precendence than the ... operator

2...5 === x is

2...(5 === x)

without parens

> **···**
>
> On May 3, 2006, at 9:13 PM, Rob Burrowes wrote:
> 
> > Hmmm, it works if I bracket the range. Why is that?

---

<div class="post-metadata">

**Author:** ![Jacob\_Fugal](https://avatars.discourse-cdn.com/v4/letter/j/439d5e/32.png) [@Jacob\_Fugal](https://rubytalk.org/u/Jacob_Fugal)\
**Post date:** [4 May 2006 15:49 UTC](https://rubytalk.org/t/newbee-question-on-what-if-x-2-5-does/27147/8 "2006-05-04T15:49:15Z")

</div>

> Hmmm, it works if I bracket the range. Why is that?

I came to the same result as others. I also figured out why you were  
getting that weird behavior when using the if statement. Let's take a  
simple test: 3 in 2...5? In irb:

> > 2...5 === 3

ArgumentError: bad value for range

> > (2...5) === 3

=\> true

Looks right, 5 === 3 was binding first, so in the first case we really  
had 2...false (since 5 === 3 is false). To verify:

> > 2...false

ArgumentError: bad value for range

So why doesn't this code:

&nbsp;&nbsp;[1,2,3,4,5,6,7,8,9,10].each do |x|  
&nbsp;&nbsp;&nbsp;&nbsp;puts x if 2...5 === x  
&nbsp;&nbsp;end

raise that exception? If I use select instead, it "works":

> > [1,2,3,4,5,6,7,8,9,10].select{ |x| 2...5 === x }

ArgumentError: bad value for range

The key is the binding again, let's look at that line with the condition again:

&nbsp;&nbsp;puts x if 2...5 === x

This is the same as

&nbsp;&nbsp;puts x if 2...(5 === x)

And since the default Object#===, which isn't overriden by the time we  
reach Integer, returns false, we have:

&nbsp;&nbsp;puts x if 2...false

regardless of x. Now, if 2...false meant a range, like it did other  
times, the Range constructor would raise the expected exception.  
\*But\*, this syntax appears as the condition of an if statement and the  
special meaning of the ... comes into play. Since 2 never "matches" (I  
think it uses the Object#=~ method here?), the switch is never turned  
on.

Whew!

Jacob Fugal

> **···**
>
> On 5/3/06, Rob Burrowes \<rob@cs.auckland.ac.nz\> wrote: