From: James Edward Gray II <james@...>
Date: 2007-04-09T21:03:57+09:00
Subject: Re: Substring like in PHP's substr()?

On Apr 9, 2007, at 6:52 AM, Joshua Muheim wrote:

> Hi all
>
> I'm looking for the coolest way to get the substring
>
> /Webwork/pgbookings
>
> out of
>
> /Users/Josh/Webwork/pgbookings
>
> The part /Users/Josh is saved in the variable my_var.
>
> In PHP I would do something like the following:
>
> substr(/Users/Josh/Webwork/pgbookings, strlen(my_var)) # =>
> /Webwork/pgbookings
>
> What's the fastest way to do this in Ruby? :-)

I'm not sure which way is faster, so let's ask Ruby to time some of  
my ideas:

#!/usr/bin/env ruby -w

require "benchmark"

data   = "/Users/Josh/Webwork/pgbookings"
prefix = "/Webwork/pgbookings"

TESTS = 1_000_000
Benchmark.bmbm do |results|
   results.report("[i..-i]:") { TESTS.times { data 
[prefix.length..-1] } }
   results.report("[i, l]:") { TESTS.times { data[prefix.length,  
data.length] } }
   results.report("sub():") { TESTS.times { data.sub(/\A#{prefix}/,  
"") } }
   results.report("[re, c]:") { TESTS.times { data[/\A#{prefix}(.+)/,  
1] } }
end
# >> Rehearsal --------------------------------------------
# >> [i..-i]:   2.500000   0.000000   2.500000 (  2.511868)
# >> [i, l]:    0.630000   0.000000   0.630000 (  0.634460)
# >> sub():     6.800000   0.020000   6.820000 (  6.850561)
# >> [re, c]:   7.180000   0.010000   7.190000 (  7.204910)
# >> ---------------------------------- total: 17.140000sec
# >>
# >>                user     system      total        real
# >> [i..-i]:   2.500000   0.000000   2.500000 (  2.500795)
# >> [i, l]:    0.630000   0.010000   0.640000 (  0.633458)
# >> sub():     6.840000   0.000000   6.840000 (  6.853133)
# >> [re, c]:   7.110000   0.010000   7.120000 (  7.130398)

__END__

Hope that helps.

James Edward Gray II