From: Hal Fulton <hal9000@...>
Date: 2003-09-14T17:50:50+09:00
Subject: Re: Does String#scan(/(..)(..)/) produce an array of arrays?

RLMuller wrote:
> Hi All,
>  
> "Programming Ruby" says the following for String#scan at 
> http://www.ruby-doc.org/docs/ProgrammingRuby/html/ref_c_string.html#String.scan:
>  
> 
> |a = "cruel world" |
> 
> |...|
> 
> |a.scan(/(..)(..)/) |�  |[["cr", "ue"], ["l ", "wo"]]|
> 
> || 
> 
> |I wrote the following to test whether scan actually produced an array 
> or arrays:|
> 
> || 
> 
> |a = "cruel world"
> ar = a.scan(/(..)(..)/)
> puts "Type of ar = %s of size %d" % [ar.class, ar.size]
> ix=0
> ar.each {|x| puts "Type of ar[#{ix}] is %s" % [ix, ar[ix].class]; ix+=1}
> |
> 
> |That resulted in:|
> 
> || 
> 
> |Type of ar = Array of size 2
> Type of ar[0] is 0
> Type of ar[1] is 1|
> 
> || 
> 
> |So it seem like we don't have an array of arrays.  So what do we have? 
> Or am I all wet?|

You're all wet. ;)

Seriously, you've just made a typo or two. Your last format string does
an interpolation instead of using a format specifier. You're printing
the value of ix as the class.

I suggest each_with_index and consistent formatting, like

ar.each_with_index {|x,ix| puts "Type of ar[#{ix}] is #{ar[ix].class}" }

If you don't like variable interpolation, you can use a real printf:

   printf "Type of ar[%d] is %s\n",ix,ar[ix].class

Anyhow, you do get real live arrays here, just as the Book says.

Hal