How to print a string with a backward slash in Ruby

Question

I have a string str = "xyz\123" and I want to print it as is.

The IRB is giving me an unexpected output. Please find the same below:-

1.9.2p290 :003 > str = "xyz\123"
 => "xyzS" 
1.9.2p290 :004 >

Any ideas on how can I get IRB to print the original string i.e. "xyz\123".

Thank you..

UPDATE :

I tried escaping it , but it doesn't seem to be that simple for some reason. Please find below my trials with the same:

1.9.2p290 :004 > str = "xyz'\'123"
 => "xyz''123" 
1.9.2p290 :005 > str = "xyz'\\'123"
 => "xyz'\\'123" 
1.9.2p290 :006 > str = "xyz'\\\'123"
 => "xyz'\\'123" 
1.9.2p290 :007 >

"Just escape it." Or, "read a tutorial". Take a pick. You may want `.inspect` as well. — , Apr 10 '12 at 04:54

Siwei · Accepted Answer · 2012-04-10T05:26:06.450

5

UPDATED answer:

escape token '\' is always working in plain ruby code, but not always working in "ruby console". so I suggest you write a unit test:

# escape_token_test.rb 
require 'test/unit'
class EscapeTokenTest < Test::Unit::TestCase
  def test_how_to_escape
    hi = "hi\\backslash"
    puts hi
  end 
end

and you will get result as:

hi\backslash

and see @pst's comment.

edited Apr 10 '12 at 05:26

answered Apr 10 '12 at 04:57

Siwei

19,858
7
75
95

1

I tried this, it doesn't work. It prints the backslash twice. Output: "xyz\\123" – boddhisattva Apr 10 '12 at 05:02
@boddhisattva That is correct. See my comment under Hophat's answer. – Apr 10 '12 at 05:07

score 3 · Answer 2 · answered Apr 10 '12 at 04:57

3

The backslash character is an escape character. You may have seen "\n" be used to display a new line, and that is why. "\123" evaulates the ASCII code for 83, which is "S". To print a backslash use 2 backslashes. So you could use str = "xyz\\123".

answered Apr 10 '12 at 04:57

Hophat Abc

5,203
3
18
18

1

I tried this, it doesn't work. It prints the backslash twice. Output: "xyz\\123" – boddhisattva Apr 10 '12 at 05:01
1

@boddhisattva Which is *correct* because the REPL prints the `.inspect` form which, for strings is the double-quoted form that can be "eval"ed back to an equivalent of the original object. Try: `puts str` and compare. – Apr 10 '12 at 05:06
@pst Thanks.. works now.. so its just that in Rails Console and IRB .. it wouldn't print as it does with "puts str" ? – boddhisattva Apr 10 '12 at 05:32

Jared Beck · Answer 3 · 2016-03-14T00:12:58.167

0

How to print a backslash?

Use 2 backslashes, e.g. "xyz\\123"

Why does "xyz\123" evaluate to "xyzS"?

In a double-quoted string, \nnn is an octal escape.

Table 22.2. Substitutions in Double-Quoted Strings

Thomas, D. (2009) Programming Ruby, p.329

So, octal 123
= (64 * 1) + (8 * 2) + 3
= decimal 83
= ASCII S

edited Mar 14 '16 at 00:12

answered Jul 20 '14 at 02:30

Jared Beck

16,796
9
72
97

1

how does this relate to printing a backslash? – max pleaner Mar 13 '16 at 06:18

score -1 · Answer 4 · answered Nov 08 '16 at 18:48

-1

It's simple ... try dump function:

mystring = %Q{"Double Quotes"}
p mystring.dump
=> "\"\\\"Double Quotes\\\"\""
p mystring
=>"\"Double Quotes\""

answered Nov 08 '16 at 18:48

Leonardo Ostan

180
1
6

How to print a string with a backward slash in Ruby

4 Answers4