From: Peter Hickman <peter@...>
Date: 2001-12-19T02:09:03+09:00
Subject: [ruby-talk:28876] Re: C++ preincrement operator

Paul Brannan wrote:

> In Ruby, if I do this:
>   x++
>
> then I get a syntax error.  However, if I do this:
>   ++x
>
> then I do not get a syntax error.  I'm guessing that Ruby parses this
> as:
>   +(+(x))
>
> which is fine, except that a seasoned C++ programmer is trained to use
> the preincrement operator, and may type this by mistake.  Would it be
> wise to have the interpreter emit a warning for this case?  I cannot
> think of any good reason to ever use ++x in an expression in Ruby.
>
> Paul

However...

x = 11
puts ++x

outputs

11

as does

x = 11
puts --x

this is not what you were expecting I suspect.

Both - and + are unary prefix operators and there is probably a 'feature'

in the parser that produces this behaviour. You will have to use

x += 1 and x -= 1