[MOAB-dev] r4250 - MOAB/trunk/tools/dagmc

[Steve Jackson]

On Nov 4, 2010, at 5:05 , Tim Tautges wrote:

> 
> 
> On 11/03/2010 11:15 PM, Paul Wilson wrote:
> 
>> Theoretically, a standard-compliant replacement could be...
>> 
>> CartVect *coords;
>> coords = new CartVect(nverts);
>> 
> 
> The disadvantage of this usage is you have to remember to delete, which can be a nuisance if you have multiple exit points.

Depending on how the compiler support for the variable-length-array syntax is implemented, calling new/delete may also have notably poorer performance. 

>> And while I am asking tutorial questions... is the original a problem
>> because the notation is only correct (in a standards compliant way) for
>> only constant sized arrays (compile time)?
>> 
> 
> Yep.  Ran across this one all the time when I taught that parallel computing course.  I wish gnu wouldn't allow that extension.

The syntax you replaced is actually valid c99, but is not formally a part of c++, nor is it likely to appear in any future revision of C++.  You can learn more about this than you wanted to know here: http://stackoverflow.com/questions/1887097/variable-length-arrays-in-c .  Still, c99 support varies widely across compilers, so even if this was a C and not a C++ context, I'd discourage the variable-length array form as being unportable.
~S