From: "David A. Black" <dblack@...>
Date: 2009-06-26T05:01:57+09:00
Subject: Re: How do I get an integer from an array?

Hi --

On Fri, 26 Jun 2009, Peter Bailey wrote:

> Brian Candler wrote:
>> Alex wrote:
>>> The index method of the array class is a method just like any other, so
>>> you
>>> could just as well write it like:
>>>
>>> foo.[](0).[](0)
>>>
>>> which calls the `[]' method on the result of the previous call of the
>>> `[]'
>>> method, which is an array.
>>>
>>> foo[0] is just a shortcut ruby gives you for calling foo.[](0)
>>
>> Or in this particular case, you can do
>>
>>   foo.first.first
>
> Well, interestingly, I've succeeded in some of my scripts. But, in this
> one, it fails. It displays a few hundred filenames with page counts,
> but, in this directory, there are literally thousands of PDF files. So,
> it does a bunch, then dies.
>
> Dir.glob("*.pdf").each do |pdffile|
> pages = `pdfinfo #{pdffile}`
> pages = pages.scan(/^Pages:[ ]{2,99}([0-9]+)/)
> pages = pages[0][0].to_i
> puts "#{pdffile}  #{pages}"
> end
>
> I get:
> ================ NoMethodError =====================
> C:\Users\pb4072\Documents\scripts\RUBY\multitiffs.rb:8:in `block in
> <main>'
>      pages = pages[0][0].to_i
> C:\Users\pb4072\Documents\scripts\RUBY\multitiffs.rb:5:in `each'
>    Dir.glob("*.pdf").each do |pdffile|
> C:\Users\pb4072\Documents\scripts\RUBY\multitiffs.rb:5:in `<main>'
>    Dir.glob("*.pdf").each do |pdffile|
>
> =============================================
> Exception: undefined method `[]' for nil:NilClass

That means that somewhere along the line, the scan operation isn't
finding what you expect it to. Is it possible that you have a document
with more than 99 occurrences of [] in a row?

I'd still recommend trying the technique I suggested in my earlier
answer. Getting a nested array of one element and unnesting it seems
like the long way around.


David

-- 
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