Ruby equivalent of PHP's “.=” (dot equals) operator

问题

In PHP we can quickly concatenate strings:

$a = "b";
$a .= "c";

which returns "bc". How would we do this in Ruby?

回答1:

irb(main):001:0> a = "ezcezc"
=> "ezcezc"
irb(main):002:0> a << "erer"
=> "ezcezcerer"

or

irb(main):003:0> a += "epruneiruv"
=> "ezcezcererepruneiruv"

回答2:

There are essentially two different ways:

1. Concatenation in place with << (known as the "shovel"), this is equivalent to calling concat. Note that, like most operators in Ruby, << is a method call.

   str = "foo"
   str << "bar"
   str  #=> "foobar"
   

2. Concatenate and assign with +=:

   str = "foo"
   str += "bar"
   str  #=> "foobar"
   

   It's important to note that this is the same as:

   str = "foo"
   str = (str + "bar")
   

   which means that with this way a new object is created, while with the first way one is not, as the object is modified in place.

回答3:

Try this out:

string += another_string

回答4:

You can do string << another_string as well

来源：https://stackoverflow.com/questions/9706903/ruby-equivalent-of-phps-dot-equals-operator