# Given a String instance, how to create a different but equivalent one

**URL:** <https://www.ruby-forum.com/t/given-a-string-instance-how-to-create-a-different-but-equivalent-one/177877>\
**Category:** Ruby\
**Created:** [October 26, 2009, 4:55am UTC](https://www.ruby-forum.com/t/given-a-string-instance-how-to-create-a-different-but-equivalent-one/177877 "2009-10-26T04:55:48Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![RichardOnRails](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e0b2c6/32.png) [@RichardOnRails](https://www.ruby-forum.com/u/RichardOnRails)\
**Post date:** [October 26, 2009, 4:55am UTC](https://www.ruby-forum.com/t/given-a-string-instance-how-to-create-a-different-but-equivalent-one/177877/1 "2009-10-26T04:55:48Z")

</div>

Given a String instance, how to create a different but equivalent one

The code below shows the incorrect way and two correct ways  
to create a second string instance that equal to a given string  
instance.

Q1: Are there better ways to do this than the two I concocted?  
Q2: How can I create a proc to invoke it with each of my candidate  
assignment statements

I am interest in this issue because I made the naive assignment in a  
project I am working on and  
had to waste time trying debugging it.

Thanks in advance,  
Richard

# Version 1: Wrong!

os = “abc” # Original String  
ws = os # Thinking ws can be modified independently of os.  
3.times { ws \<\< (ws[-1] + 1).chr; puts ws }  
while ws.size \> os.size  
ws.chop; puts ws  
end

# Version 2: OK

puts  
os = “abc” # Original String  
ws = String.new(os) # ws is a reference to a different string  
oobject than os but initially equal to os  
3.times { ws \<\< (ws[-1] + 1).chr; puts ws }  
while ws.size \> os.size  
ws.chop!; puts ws  
end

# Version 3: OK

puts  
os = “abc” # Original String  
ws = os + “” # A less verbose way to get a new string object  
initially equal to os  
3.times { ws \<\< (ws[-1] + 1).chr; puts ws }  
while ws.size \> os.size  
ws.chop!; puts ws  
end

---

<div class="post-metadata">

**Author:** ![RichardOnRails](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e0b2c6/32.png) [@RichardOnRails](https://www.ruby-forum.com/u/RichardOnRails)\
**Post date:** [October 26, 2009, 6:14am UTC](https://www.ruby-forum.com/t/given-a-string-instance-how-to-create-a-different-but-equivalent-one/177877/2 "2009-10-26T06:14:12Z")

</div>

RichardOnRails wrote:

> I am interest in this issue because I made the naive assignment in a  
> ws = os # Thinking ws can be modified independently of os.  
> oobject than os but initially equal to os  
> initially equal to os  
> 3.times { ws \<\< (ws[-1] + 1).chr; puts ws }  
> while ws.size \> os.size  
> ws.chop!; puts ws  
> end

Use String.dup to create a copy

irb(main):050:0\> s1=‘hello’  
=\> “hello”  
irb(main):050:0\> s2=s1  
=\> “hello”  
irb(main):049:0\> s1.eql? s2  
=\> true  
irb(main):048:0\> s1.equal? s2  
=\> true

irb(main):047:0\> s3=s1.dup  
=\> “hello”  
irb(main):046:0\> s3  
=\> “hello”  
irb(main):045:0\> s3.eql? s1  
=\> true  
irb(main):044:0\> s3.equal? s1  
=\> false

–  
Kind Regards,  
Rajinder Y.

[http://DevMentor.org](http://DevMentor.org)

Do Good! - Share Freely, Enrich and Empower people to Transform their  
lives.

---

<div class="post-metadata">

**Author:** ![RichardOnRails](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/r/e0b2c6/32.png) [@RichardOnRails](https://www.ruby-forum.com/u/RichardOnRails)\
**Post date:** [October 26, 2009, 2:45pm UTC](https://www.ruby-forum.com/t/given-a-string-instance-how-to-create-a-different-but-equivalent-one/177877/3 "2009-10-26T14:45:51Z")

</div>

On Oct 26, 1:13 am, Rajinder Y. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> > ws = os # Thinking ws can be modified independently of os.  
> > oobject than os but initially equal to os  
> > initially equal to os  
> > =\> “hello”  
> > =\> true  
> > irb(main):044:0\> s3.equal? s1  
> > =\> false
> 
> –  
> Kind Regards,  
> Rajinder Y.
> 
> [http://DevMentor.org](http://DevMentor.org)
> 
> Do Good! - Share Freely, Enrich and Empower people to Transform their lives.

Hi Rajinder ,

> Use String.dup to create a copy

Thanks. I “knew” there was a “right way” in Ruby.

Best wishes,  
Richard