[ruby] No increment operator (++) in Ruby?

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Why doesn't Ruby support i++ or i— for fixnum?

Why is there no increment operator in Ruby?

e.g.

i++
++i

Is the ++ operator used for something else? Is there a real reason for this?

This question is related to ruby operators

The answer is


From a posting by Matz:

(1) ++ and -- are NOT reserved operator in Ruby.

(2) C's increment/decrement operators are in fact hidden assignment. They affect variables, not objects. You cannot accomplish assignment via method. Ruby uses +=/-= operator instead.

(3) self cannot be a target of assignment. In addition, altering the value of integer 1 might cause severe confusion throughout the program.

                      matz.

I don't think that notation is available because—unlike say PHP or C—everything in Ruby is an object.

Sure you could use $var=0; $var++ in PHP, but that's because it's a variable and not an object. Therefore, $var = new stdClass(); $var++ would probably throw an error.

I'm not a Ruby or RoR programmer, so I'm sure someone can verify the above or rectify it if it's inaccurate.


Ruby has no pre/post increment/decrement operator. For instance, x++ or x-- will fail to parse. More importantly, ++x or --x will do nothing! In fact, they behave as multiple unary prefix operators: -x == ---x == -----x == ...... To increment a number, simply write x += 1.

Taken from "Things That Newcomers to Ruby Should Know " (archive, mirror)

That explains it better than I ever could.

EDIT: and the reason from the language author himself (source):

  1. ++ and -- are NOT reserved operator in Ruby.
  2. C's increment/decrement operators are in fact hidden assignment. They affect variables, not objects. You cannot accomplish assignment via method. Ruby uses +=/-= operator instead.
  3. self cannot be a target of assignment. In addition, altering the value of integer 1 might cause severe confusion throughout the program.