单引号与双引号

Question

I am trying to split a string by three consecutive newlines ( "\\n\\n\\n" ). I was trying str.split('\\n\\n\\n') and it didn't work, but when I changed to str.split("\\n\\n\\n") , it started to work. Could anyone explain to me why such behaviour happens?

Answer 1

String in single quotes is a raw string. So '\\n\\n\\n' is three backslashes and three n , not three line feeds as you expected. Only double quotes string can be escaped correctly.

puts 'abc\nabc'  # => abc\nabc
puts "abc\nabc"  # => abc
                 #    abc

Answer 2

Single quoted string have the actual/literal contents, eg

1.9.3-p194 :003 > puts 'Hi\nThere'
Hi\nThere
 => nil 

Whereas double-quoted string 'interpolate' the special characters (\\n) and do the line feed, eg

1.9.3-p194 :004 > puts "Hi\nThere"
Hi
There
 => nil 
1.9.3-p194 :005 > 

Best practice Recommendations:

• Choose single quotes over double quotes when possible (use double quotes as needed for interpolation).
• When nesting 'Quotes inside "quotes" somewhere' put the double ones inside the single quotes

Answer 3

在单引号字符串文字中，反斜杠不需要加倍

'\n' == '\\n'