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From: Ioannis Vranos <ivr@remove.this.grad.com>
Newsgroups: comp.lang.ada,comp.lang.c++,comp.realtime,comp.software-eng
Subject: Re: Teaching new tricks to an old dog (C++ -->Ada)
Date: Wed, 09 Mar 2005 11:49:02 +0200
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Date: 2005-03-09T11:49:02+02:00
List-Id: <comp.lang.ada>

Pascal Obry wrote:

>>The C++ equivalent:
>>
>>
>>#include <vector>
>>
>>// ...
>>
>>
>>using namespace std;
>>
>>vector<int> Data(10);
>>
>>for(vector<int>::size_type i=0; i<Data.size(); ++i)
>>{
>>     if (Data[i]== 1)
> 
> 
> And no C++ compiler will check that Data[i] is valid. That's the point. If you
> add the check explicitly no C++ compiler will be able to remove it. In the Ada
> case the compiler knows lot more about the program and can decide to remove
> the check if it knows that the index will never be outside the object
> range. This is always the case for:
> 
>    for K in Data'Range loop
>       ... Data(k)...
> 
> Pascal.



I suppose this run-time check is something like the one provided by .NET 
(mentioned in another message of mine).


ISO C++ speaking, one may use vector::at() which provides boundary 
checking, however the aforementioned way is *always* 100% safe as well 
as the following:


#include <vector>

// ...


using namespace std;

vector<int> Data(10);


for(vector<int>::iterator p= Data.begin(); p!=Data.end(); ++p)
{
     if (*p== 1)
     {
         // ...
     }
}



-- 
Ioannis Vranos

http://www23.brinkster.com/noicys