how to copy array in ruby
PIKI
I am a novice in Ruby programming so this question might look trivial
to lot of people.
But I am struggling to copy an array.
I am using
a = []
b = a
/* some manipulation here on "b" and "a" I havent touched at all*/
Here when i am trying to see contents of "a" and "b" both have same
contents
But my expectation was they shud be different
Instead of b = a, I also tried b.replace(a)
but no luck here also.
Please help me on how to make a duplicate("b") of "a" so that changes
done on b will not affect a
Thanks
Pikender Sharma
Jesús Gabriel y Galán
> But I am struggling to copy an array.
>
> I am using
>
> a = []
> b = a
>
> /* some manipulation here on "b" and "a" I havent touched at all*/
>
> Here when i am trying to see contents of "a" and "b" both have same
> contents
>
> But my expectation was they shud be different
>
> Instead of b = a, I also tried b.replace(a)
>
> but no luck here also.
>
> Please help me on how to make a duplicate("b") of "a" so that changes
> done on b will not affect a
irb(main):001:0> a = [1,2,3,4]
=> [1, 2, 3, 4]
irb(main):002:0> b = a.dup
=> [1, 2, 3, 4]
irb(main):003:0> b[0] = 55
=> 55
irb(main):004:0> a
=> [1, 2, 3, 4]
irb(main):005:0> b
=> [55, 2, 3, 4]
Hope this helps,
Jesus.
PIKI
wrote:
>
> - Show quoted text -
Hi Jesús Gabriel y Galán
Thanks for the reply and help
I tried ur solution but it is also not working :(
I am unable to figure out the trick
Thanks
Pikender Sharma
lith
>
> I am unable to figure out the trick
In order to help us to figure out what is the problem, you might want
to post a code snippet demonstrating the defect and explain what how
you would expect ruby to behave.
Array#dup creates a copy of the array, not of the elements in the
array, aka a shallow copy.
Ralph Shnelvar
l> array, aka a shallow copy.
Is there a way to make a deep copy? That is ... in the code below,
could b.dup be replaced with something like b.deepdup?
irb(main):019:0> a1 = [1,2,3,4]
=> [1, 2, 3, 4]
irb(main):020:0> b = [a1,5]
=> [[1, 2, 3, 4], 5]
irb(main):021:0> c1 = b
=> [[1, 2, 3, 4], 5]
irb(main):022:0> c2 = b.dup
=> [[1, 2, 3, 4], 5]
irb(main):023:0> a1[0] = "hi"
=> "hi"
irb(main):024:0> a1
=> ["hi", 2, 3, 4]
irb(main):025:0> c1
=> [["hi", 2, 3, 4], 5]
irb(main):026:0> c2
# because of the shallow copy, c2[0][0] is "hi" instead of a naively
# assumed 1.
=> [["hi", 2, 3, 4], 5]
irb(main):027:0> c1[1] = "bye"
=> "bye"
irb(main):028:0> c1
=> [["hi", 2, 3, 4], "bye"]
irb(main):029:0> c2
# The shallow copy gives the expected result for c2[1], below.
=> [["hi", 2, 3, 4], 5]
