Inconsistent behaviour when working with a string

Hi List,

I'm writing a supposedly simple program to help me sort some files in to 
a different data structure.
I have ~2 million files that look either like this
access1202241814.merged.log.bz2
or this
access_denied1202211457.merged.log.bz2

Though over 90% or of the first type I'd like to be able to handle both 
at the same time as this will eventually form part of a larger log 
management program.

This is what I currently have

$months = ['01-January', '02-February', '03-March', '04-April', 
'05-May', '06-June', '07-July', '08-August', '09-September', 
'10-October', '11-November', '12-December']
Dir.chdir("/ruby-scripts/archive/logs/misc/")
Dir.foreach(".") do |file|
fileint = file[/\d{10,}/]
year = fileint[0,2]
month = $months[fileint[2,2].to_i-1]
puts "year = #{year} month = #{month} and file was #{file}"
end

this will return
./archive.rb:7:in `block in <main>': undefined method `[]' for 
nil:NilClass (NoMethodError)

I don't understand why though as the example below works fine, but will 
only match access1202241814.merged.log.bz2

$months = ['01-January', '02-February', '03-March', '04-April', 
'05-May', '06-June', '07-July', '08-August', '09-September', 
'10-October', '11-November', '12-December']
Dir.chdir("/ruby-scripts/archive/logs/misc/")
Dir.foreach(".") do |file|
year = file[0,2]
month = $months[file[2,2].to_i-1]
puts "year = #{year} month = #{month} and file was #{file}"
end

The only difference between the 2 is that in the first one I've used a 
regex to strip out all the extraneous text.
I've tried this in ruby 1.9.2 and 1.8.7

Can any one explain why the 1 one is breaking? and if this is expected 
behaviour, is there a way I can do this so it will cope with both file 
types at the same time?

Thanks for any pointers

Regards,

Tris

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