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Array indexing

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  Array indexing Duke Normandin <dukeofperl@ml1.net> - 2011-04-23 11:22 -0500
    Re: Array indexing 7stud -- <bbxx789_05ss@yahoo.com> - 2011-04-23 12:02 -0500
    Re: Array indexing Josh Cheek <josh.cheek@gmail.com> - 2011-04-23 12:37 -0500
      Re: Array indexing Duke Normandin <dukeofperl@ml1.net> - 2011-04-23 13:12 -0500

#3403 — Array indexing

hey ...

I want to make sure that I understand the subtle difference in the
syntax.

my_array[0,3]

and

my_array[0..2]

both will return the same array elements - correct?

the first _says_: "start at index0 & gimme 3"
the latter _say_: "start at index0 and goto index2"

If the data requirements start at >index0, then there is no offset
between the "gimme" and the 'goto".

Am I getting it?
-- 
Duke

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#3404

Duke Normandin wrote in post #994657:
> hey ...
>
> I want to make sure that I understand the subtle difference in the
> syntax.
>
> my_array[0,3]
>
> and
>
> my_array[0..2]
>
> both will return the same array elements - correct?
>

If someone had a gun to your head and told you that you had 30 seconds 
to provide an answer to that question, what would you do?

> the first _says_: "start at index0 & gimme 3"
> the latter _say_: "start at index0 and goto index2"
>

Where is the ruby documentation located?


> If the data requirements start at >index0, then there is no offset
> between the "gimme" and the 'goto".
>
> Am I getting it?

No.

-- 
Posted via http://www.ruby-forum.com/.

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#3409

[Note:  parts of this message were removed to make it a legal post.]

On Sat, Apr 23, 2011 at 11:22 AM, Duke Normandin <dukeofperl@ml1.net> wrote:

> hey ...
>
> I want to make sure that I understand the subtle difference in the
> syntax.
>
> my_array[0,3]
>
> and
>
> my_array[0..2]
>
> both will return the same array elements - correct?
>
> the first _says_: "start at index0 & gimme 3"
> the latter _say_: "start at index0 and goto index2"
>
> If the data requirements start at >index0, then there is no offset
> between the "gimme" and the 'goto".
>
> Am I getting it?
> --
> Duke
>
>
IDK, but a quick study of behaviour should make it very obvious:


numbers = *0...10 # => [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

numbers[0,3] # => [0, 1, 2]
numbers[1,3] # => [1, 2, 3]
numbers[2,3] # => [2, 3, 4]
numbers[3,3] # => [3, 4, 5]


numbers[0,4] # => [0, 1, 2, 3]
numbers[1,4] # => [1, 2, 3, 4]
numbers[2,4] # => [2, 3, 4, 5]
numbers[3,4] # => [3, 4, 5, 6]


numbers[0..5] # => [0, 1, 2, 3, 4, 5]
numbers[1..5] # => [1, 2, 3, 4, 5]
numbers[2..5] # => [2, 3, 4, 5]
numbers[3..5] # => [3, 4, 5]


numbers[3..7] # => [3, 4, 5, 6, 7]
numbers[4..7] # => [4, 5, 6, 7]
numbers[5..7] # => [5, 6, 7]
numbers[6..7] # => [6, 7]
numbers[7..7] # => [7]


If you're using TextMate, you can update the comments with
command+control+shift+e. Otherwise, you might try entering each line into
irb, and it will update for you the correct value. Or you could write a
program to cycle through inputs and print the values, something like:

numbers = *0...10

(0..3).each do |start|
  result = numbers[start,3]
  puts "numbers[#{start},3] # => #{result.inspect}"
end


On Sat, Apr 23, 2011 at 12:02 PM, 7stud -- <bbxx789_05ss@yahoo.com> wrote:

>
> If someone had a gun to your head and told you that you had 30 seconds
> to provide an answer to that question, what would you do?
>
>
Ruby is serious business.

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#3411

On Sun, 24 Apr 2011, Josh Cheek wrote:

> On Sat, Apr 23, 2011 at 11:22 AM, Duke Normandin <dukeofperl@ml1.net> wrote:
>
> > hey ...
> >
> > I want to make sure that I understand the subtle difference in the
> > syntax.

[snip]

> >
> IDK, but a quick study of behaviour should make it very obvious:
>
>

[snip the good stuff]

>

Thanks for _all_ that!

However, I think that I summarized it in my original post, exactly as
you are showing it above. My definition of "gimme" and "goto" may not
be as clear as what I had hoped it would be. No matter! I'll check my
understanding of the issue against what you've provided above. Much
obliged!
-- 
Duke

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