Strings in Ruby - Concatenating Strings

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In Ruby, you can add on to an existing string with various concatenation techniques. With Ruby, you don’t have to jump through the hoops that you might if you were using a language with immutable strings.

Adjacent strings can be concatenated simply because that they are next to each other:

  "Hello," " " "Matz" "!" # => "Hello, Matz!"

You can also use the+ method:

  "Hello," + " " + "Matz" + "!" # => "Hello, Matz!"

You can even mix double and single quotes, as long as they are properly paired.

Another way to do this is with the<<method. You can add a single string:

  "Hello, " << "Matz!" # => Hello, Matz!

Or you can chain them together with multiple calls to<<:

  "Hello," << " " << "Matz" << "!" # => Hello, Matz!

An alternative to<<is theconcatmethod (which does not allow you to chain):

  "Hello, ".concat "Matz!"

Or you can do it this way:

  h = "Hello,"
  m = "Matz!"
  h.concat(m)

You can make a string immutable withObject’sfreezemethod:

  greet = "Hello, Matz!"
  greet.freeze

  # try to append something
  greet.concat("!") # => TypeError: can't modify frozen string

  # is the object frozen?
  greet.frozen? # => true

Next: Accessing Strings >>
 

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