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comp.lang.ruby

regualr expression question

Reg

4/16/2009 10:37:00 PM

The "Ruby_RegularExpression" sample application in the
javapassion rubyonrails tutorial has this code

puts "----Regular Expression"
puts a = "hello there"
puts a[1] #=> 101
puts a[1,3] #=> "ell"

How do you get 101 from a[1]
2 Answers

Mike Stok

4/16/2009 11:03:00 PM

0


On Apr 16, 2009, at 6:40 PM, Reg wrote:

> The "Ruby_RegularExpression" sample application in the
> javapassion rubyonrails tutorial has this code
>
> puts "----Regular Expression"
> puts a = "hello there"
> puts a[1] #=> 101
> puts a[1,3] #=> "ell"
>
> How do you get 101 from a[1]

It's the value associated with the character e in ASCII.

In irb:

> RUBY_VERSION
=> "1.8.6"
>> a = 'hello'
=> "hello"
>> a[1]
=> 101
>> ?e
=> 101
>> a[1 ,1]
=> "e"
>>


If you look at the ri documnetation for String#[] in Ruby 1.8.6 you
can see:

-------------------------------------------------------------- String#[]
str[fixnum] => fixnum or nil
str[fixnum, fixnum] => new_str or nil
str[range] => new_str or nil
str[regexp] => new_str or nil
str[regexp, fixnum] => new_str or nil
str[other_str] => new_str or nil
[...]
------------------------------------------------------------------------
Element Reference---If passed a single +Fixnum+, returns the code
of the character at that position.
[...]

In Ruby 1.9 things change so that you always get a String or nil back
from String#[]:

irb(main):001:0> RUBY_VERSION
=> "1.9.2"
irb(main):002:0> a = 'hello'
=> "hello"
irb(main):003:0> a[1]
=> "e"
irb(main):004:0>

Hope this helps,

Mike

--

Mike Stok <mike@stok.ca>
http://www.stok...

The "`Stok' disclaimers" apply.

Reg

4/16/2009 11:21:00 PM

0

On Thu, 16 Apr 2009 18:02:52 -0500, Mike Stok <mike@stok.ca> wrote:


>> How do you get 101 from a[1]
>
>It's the value associated with the character e in ASCII.
>
>In irb:
>
> > RUBY_VERSION
>=> "1.8.6"
> >> a = 'hello'
>=> "hello"
> >> a[1]
>=> 101
> >> ?e
>=> 101
> >> a[1 ,1]
>=> "e"
> >>
>
>
>If you look at the ri documnetation for String#[] in Ruby 1.8.6 you
>can see:
>
>-------------------------------------------------------------- String#[]
> str[fixnum] => fixnum or nil
> str[fixnum, fixnum] => new_str or nil
> str[range] => new_str or nil
> str[regexp] => new_str or nil
> str[regexp, fixnum] => new_str or nil
> str[other_str] => new_str or nil
>[...]
>------------------------------------------------------------------------
> Element Reference---If passed a single +Fixnum+, returns the code
> of the character at that position.
>[...]
>
>In Ruby 1.9 things change so that you always get a String or nil back
>from String#[]:
>
>irb(main):001:0> RUBY_VERSION
>=> "1.9.2"
>irb(main):002:0> a = 'hello'
>=> "hello"
>irb(main):003:0> a[1]
>=> "e"
>irb(main):004:0>
>
>Hope this helps,
>
>Mike

Its a great help!
Thanks Mike