Hi,
Please excuse the newbie question, but I am confused by something I see with
sub!() (this seems to be true with other "!" operations as well):
irb(main):001:0> string1 = "hello"
=> "hello"
irb(main):002:0> string2 = string1
=> "hello"
irb(main):003:0> string2.sub!(/e/,"a")
=> "hallo"
irb(main):004:0> string2
=> "hallo"
irb(main):005:0> string1
=> "hallo"
irb(main):006:0>
Why is string1 also changed when sub!() is being performed on string2 ?
Shouldn't sub!() only be acting on the string it is being called on?
Thanks,
Martin
when writing :
string2 = string1
both your variables reference the same address , so , modifications to
any of them will cause modification to the other .
If you write :
string2 = string1.clone
then you will modify just string2 , when writing sub!
···
--
Posted via http://www.ruby-forum.com/.
when writing :
string2 = string1
both your variables reference the same address , so , modifications to
any of them will cause modification to the other .
If you write :
string2 = string1.clone
then you will modify just string2 , when writing sub!
--
Posted via http://www.ruby-forum.com/\.
But, why then, the following is not true???
n1 = 100
n2 = n2
To this point the are the same, including the object_id.
But when I assign:
n2 = 200
The n1 does not change and the object_id of n2 change.
Please see the irb session below.
irb
irb(main):001:0> n1 = 100
=> 100
irb(main):002:0> n2 = n1
=> 100
irb(main):003:0> p n1
100
=> nil
irb(main):004:0> p n2
100
=> nil
irb(main):005:0> p n1.object_id
201
=> nil
irb(main):006:0> p n2_object_id
NameError: undefined local variable or method `n2_object_id' for main:Object
from (irb):6
irb(main):007:0> p n2.object_id
201
=> nil
irb(main):008:0> n2 = 200
=> 200
irb(main):009:0> p n1
100
=> nil
irb(main):010:0> p n2
200
=> nil
irb(main):011:0> p n1.object_id
201
=> nil
irb(main):013:0> p n2.object_id
401
=> nil
irb(main):014:0>
Thank you
Ruby Student
···
On Sun, Oct 5, 2008 at 6:37 AM, Lex Williams <etaern@yahoo.com> wrote:
from :0
Hi --
when writing :
string2 = string1
both your variables reference the same address , so , modifications to
any of them will cause modification to the other .
If you write :
string2 = string1.clone
then you will modify just string2 , when writing sub!
--
Posted via http://www.ruby-forum.com/\.
But, why then, the following is not true???
n1 = 100
n2 = n2
To this point the are the same, including the object_id.
But when I assign:
n2 = 200
The n1 does not change and the object_id of n2 change.
When you assign to a variable, you break any previous binding the
variable had.
a = "string"
b = a #1
b = 100 #2
At #1, the identifiers 'a' and 'b' refer to the same object. At #2,
however, 'b' has been bound to another object. Nothing you do to the
string in a will affect the object in b (100).
David
···
On Sun, 5 Oct 2008, Ruby Student wrote:
On Sun, Oct 5, 2008 at 6:37 AM, Lex Williams <etaern@yahoo.com> wrote:
--
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Intro to Ruby on Rails January 12-15 Fort Lauderdale, FL
Advancing with Rails January 19-22 Fort Lauderdale, FL *
* Co-taught with Patrick Ewing!
See http://www.rubypal.com for details and updates!