Re: [boost] Towards a Warning free code policy proposal

Subject: Re: [boost] Towards a Warning free code policy proposal
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2010-08-29 05:50:54

On 28/08/2010 22:11, Mika Heiskanen wrote:
> On Sat, 2010-08-28 at 22:17 +0300, Robert Ramey wrote:
>> d) some were too hard to fix/eliminate comparison between signed/unsigned -
>> I just left them because I didn't know how to fix them

Comparing signed and unsigned integers can be a serious issue, since 
that means you might not deal with negative cases properly, which is why 
there are warnings.

> Am I missing some complication I'm not aware of?
>
> In my experience this warning is just about always the result of
> using int for variables which should be of type size_t, as in
>
>    for(int i=0; i<object.size(); i++)

I never understood why some people even write code like this.
There are several problems with this:
  - using int, even though int has no direct relation with the size type 
of 'object'
  - using indexes and size instead of iterators, which have an idiomatic 
way to be traversed
  - making the code rely on a particular data structure, instead of 
allowing it to work with any sequence type, allowing the code to be more 
easily changed.

> If I cannot redefine all the types to unsigned, something like this
> usually fixes the problem:
>
>    if ( size>= 0&&  static_cast<size_t>(size)<  object.size() )

size_t(size) instead of static_cast<size_t>(size) should work just fine.
No need for any cast.