Re: [boost] [optional] memory use for optional refs and ptrs

Subject: Re: [boost] [optional] memory use for optional refs and ptrs
From: Larry Evans (cppljevans_at_[hidden])
Date: 2010-10-06 14:05:40

On 10/06/10 08:28, Sebastian Redl wrote:
> On 06.10.2010 14:26, Stewart, Robert wrote:
[snip]
>> When the bool follows the value, it can occupy otherwise unused
>> padding between data members.
>>    
> I really don't think so. Maybe in theory, but not in practice,
[snip]
A copy of the code posted here:

  http://article.gmane.org/gmane.comp.lib.boost.devel/209212

followed by:

struct C {
    int a;
    bool ta;
    double b;
    bool tb;
    double c;
    bool tc;
    std::string d;
    bool td;
};

int main(void)
{
    std::cout<<"sizeof(A)="<<sizeof(A)<<"\n";
    std::cout<<"sizeof(B)="<<sizeof(B)<<"\n";
    std::cout<<"sizeof(C)="<<sizeof(C)<<"\n";
    return 0;
}

showed sizeof(B) = sizeof(C), justifying Sebastian's doubt.

-Larry