# Characters and strings oddness

**URL:** <https://www.ruby-forum.com/t/characters-and-strings-oddness/106864>\
**Category:** Ruby\
**Created:** [June 14, 2007, 8:02pm UTC](https://www.ruby-forum.com/t/characters-and-strings-oddness/106864 "2007-06-14T20:02:25Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Stefan\_Kruger](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ba9def/32.png) [@Stefan\_Kruger](https://www.ruby-forum.com/u/Stefan_Kruger)\
**Post date:** [June 14, 2007, 8:02pm UTC](https://www.ruby-forum.com/t/characters-and-strings-oddness/106864/1 "2007-06-14T20:02:25Z")

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Hi there Rubyists -

I’m trying to learn the language, coming from a long background in Perl.

Here’s what I want to do: pick out a double-quoted string inside  
another string,  
respecting embedded, backslashed quotes:

line = ’ a string “properly “quoted” that ends” here ’  
quoted = ‘“properly “quoted” that ends”’

If Ruby had the same regexes as Perl, I’d say something like

line.gsub!(/^\s\*("._?(?\<!\)")\s_/, ‘’)

and have my quoted string pop out in $1. In fact, TextMate groks that  
regex, too.  
Ruby don’t like the negative look-behind, unfortunately.

Ok, let’s do a loop then. I finally arrived at:

string = “”"  
if line.gsub!(/^.\*?(")/, ‘’)  
(0…line.length).each do |i|  
string \<\< line[i]  
break if i\>0 && (line[i, 1] == “”") && (line[i-1, 1] != ‘\’)  
end  
end

which works. However… I’m puzzled by Ruby’s way of handling strings. A  
string  
is - essentially - a set of bytes, not unlike a char[] in C. Is there  
really no way  
of defining character literals in Ruby? I was surprised to find that I  
couldn’t say

Stefan-Krugers-Computer:~ stefan$ irb  
irb(main):001:0\> string = ‘this is a string’  
=\> “this is a string”  
irb(main):002:0\> string[0] == ‘t’  
=\> false

whereas i _can_ say

irb(main):003:0\> string[0, 1] == ‘t’  
=\> true

Now, in my little loop experiment above I tried the following:

delim = “”"  
string = delim  
if line.gsub!(/^.\*?(")/, ‘’)  
(0…line.length).each do |i|  
string \<\< line[i]  
break if i\>0 && (line[i, 1] == delim) && (line[i-1, 1] != ‘\’)  
end  
end

TypeError: can’t convert nil into String

method \<\< in test.rb at line 9  
at top level in test.rb at line 9  
at top level in test.rb at line 8

I’m at a loss to understand why that gives an error.

---

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**Author:** ![Stefan\_Kruger](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ba9def/32.png) [@Stefan\_Kruger](https://www.ruby-forum.com/u/Stefan_Kruger)\
**Post date:** [June 14, 2007, 8:28pm UTC](https://www.ruby-forum.com/t/characters-and-strings-oddness/106864/2 "2007-06-14T20:28:30Z")

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On Jun 14, 2007, at 11:01 AM, Stefan Kruger wrote:

> Hi there Rubyists -  
> Hi.

> irb(main):002:0\> string[0] == ‘t’  
> string[0].chr == ‘t’  
> or  
> string[0] == ?t

> method \<\< in test.rb at line 9  
> at top level in test.rb at line 9  
> at top level in test.rb at line 8
> 
> I’m at a loss to understand why that gives an error.  
> Try 0…line.length (three dots, not two). You’re indexing past the  
> end of the string.

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<div class="post-metadata">

**Author:** ![Stefan\_Kruger](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ba9def/32.png) [@Stefan\_Kruger](https://www.ruby-forum.com/u/Stefan_Kruger)\
**Post date:** [June 14, 2007, 9:55pm UTC](https://www.ruby-forum.com/t/characters-and-strings-oddness/106864/3 "2007-06-14T21:55:48Z")

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On Jun 14, 12:27 pm, Zachary H. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> On Jun 14, 2007, at 11:01 AM, Stefan Kruger wrote:
> 
> > irb(main):002:0\> string[0] == ‘t’
> 
> string[0].chr == ‘t’  
> or  
> string[0] == ?t

or string[0…0] == ‘t’

It’s a common gotcha that indexing a string by a single integer  
returns the (integer) CODE of the character/byte at that location, not  
the one-character string containing that byte.

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<div class="post-metadata">

**Author:** ![Stefan\_Kruger](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ba9def/32.png) [@Stefan\_Kruger](https://www.ruby-forum.com/u/Stefan_Kruger)\
**Post date:** [June 15, 2007, 2:19am UTC](https://www.ruby-forum.com/t/characters-and-strings-oddness/106864/4 "2007-06-15T02:19:00Z")

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Stefan Kruger wrote:

> line = ’ a string “properly “quoted” that ends” here ’  
> quoted = ‘“properly “quoted” that ends”’
> 
> If Ruby had the same regexes as Perl, I’d say something like
> 
> line.gsub!(/^\s\*("._?(?\<!\)")\s_/, ‘’)
> 
> and have my quoted string pop out in $1. In fact, TextMate groks that  
> regex, too.

How is that supposed to work? With the initial anchor there’s no way  
that regexp would ever match even if ruby supported look-behind. I  
suggest this: /"((?:\.|[^\])+)"/

Daniel