besides `%w[1 2 3]` what other methods or tricks exist that use % then some letter? in ruby

In Ruby, besides %w which is used to create an array of strings, there are several other notations that use the % character followed by a letter. Here are some of them:

1. %q or %Q: These notations are used to create a single-quoted or double-quoted string, respectively. They are useful when you have a string that contains many special characters and you want to avoid escaping them. For example:

   main.rb
   puts %q(You don't need to escape single quotes in this string)
   puts %Q(You can include double quotes "here" without escaping them)
   131 chars
   3 lines

2. %r: This notation is used to create a regular expression. It allows you to define a regular expression pattern without the need for explicitly using the Regexp.new constructor. For example:

   main.rb
   pattern = %r(\d{3}-\d{3}-\d{4})
   puts "Valid phone number" if "555-123-4567" =~ pattern
   87 chars
   3 lines

3. %s: This notation is used to create a symbol, which is a lightweight constant in Ruby. It is similar to a string but immutable and unique. For example:

   main.rb
   my_symbol = %s(foo)
   puts my_symbol #=> :foo
   44 chars
   3 lines

4. %i or %I: These notations are used to create an array of symbols. %i creates symbols without interpolation, while %I allows for interpolation. For example:

   main.rb
   name = "Alice"
   symbols = %i[hello #{name} goodbye]
   puts symbols #=> [:hello, :"\#{name}", :goodbye]
   100 chars
   4 lines

These notations provide a convenient way to create certain types of objects in Ruby. They are especially helpful when you have strings or patterns that contain characters that would normally require escaping.