Ruby Programming/Alternate quotes

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In Ruby, there's more than one way to quote a string literal. Much of this will look familiar to Perl programmers.

Alternate single quotesEdit

Let's say we are using single quotes to print out the following path.

puts 'c:\bus schedules\napolean\the portland bus schedule.txt'

The single quotes keep the \b, \n, and \t from being treated as escape sequences (the same cannot be said for wikibooks' syntax highlighting). But consider the following string literal.

puts 'c:\napolean\'s bus schedules\tomorrow\'s bus schedule.txt'

Escaping the apostrophes makes the code less readable and makes it less obvious what will print out. Luckily, in Ruby, there's a better way. You can use the %q operator to apply single-quoting rules, but choose your own delimiter to mark the beginning and end of the string literal.

puts %q!c:\napolean's documents\tomorrow's bus schedule.txt!
puts %q/c:\napolean's documents\tomorrow's bus schedule.txt/
puts %q^c:\napolean's documents\tomorrow's bus schedule.txt^
puts %q(c:\napolean's documents\tomorrow's bus schedule.txt)
puts %q{c:\napolean's documents\tomorrow's bus schedule.txt}
puts %q<c:\napolean's documents\tomorrow's bus schedule.txt>

Each line will print out the same text – "c:\napolean's documents\tomorrow's bus schedule.txt". You can use any punctuation you want as a delimiter, not just the ones listed in the example.

Of course, if your chosen delimiter appears inside of the string literal, then you need to escape it.

puts %q#c:\napolean's documents\tomorrow's \#9 bus schedule.txt#

If you use matching braces to delimit the text, however, you can nest braces, without escaping them.

puts %q(c:\napolean's documents\the (bus) schedule.txt)
puts %q{c:\napolean's documents\the {bus} schedule.txt}
puts %q<c:\napolean's documents\the <bus> schedule.txt>

Alternate double quotesEdit

The %Q operator (notice the case of Q in %Q) allows you to create a string literal using double-quoting rules, but without using the double quote as a delimiter. It works much the same as the %q operator.

print %Q^Say:\tHello world\n\tHello world\n^
print %Q(Say:\tHello world\n\tHello world\n)

Just like double quotes, you can interpolate Ruby code inside of these string literals.

name = 'Charlie Brown'

puts %Q!Say "Hello," #{name}.!
puts %Q/What is "4 plus 5"? Answer: #{4+5}/