Are strings in Ruby mutable? [duplicate]
Yes, strings in Ruby, unlike in Python, are mutable.
s += "hello" is not appending "hello" to s - an entirely new string object gets created. To append to a string 'in place', use <<, like in:
s = "hello"s << " world"s # hello world
ruby-1.9.3-p0 :026 > s="foo" => "foo" ruby-1.9.3-p0 :027 > s.object_id => 70120944881780 ruby-1.9.3-p0 :028 > s<<"bar" => "foobar" ruby-1.9.3-p0 :029 > s.object_id => 70120944881780 ruby-1.9.3-p0 :031 > s+="xxx" => "foobarxxx" ruby-1.9.3-p0 :032 > s.object_id => 70120961479860 so, Strings are mutable, but += operator creates a new String. << keeps old
Appending in Ruby String is not +=, it is <<
So if you change += to << your question gets addressed by itself