Re: Converting new [] to vectors

From:

Juan Pedro Bolivar Puente <magnicida@gmail.com>

Newsgroups:

comp.lang.c++.moderated

Date:

Tue, 2 Mar 2010 18:18:24 CST

Message-ID:

<4B8D7F7F.9050102@gmail.com>

On 02/03/10 15:26, Francis Glassborow wrote:

Mathias Gaunard wrote:

On 1 mar, 21:26, Richard Howard wrote:

I would be inclined to do something like this:
struct Point3D
{
     float value[3];
     float operator[](int i) const { return value[i]; }
     float& operator[](int i) { return value[i]; }
};
vector<Point3D> coords;
coords.resize(sourceOfPoints->size());
sourceOfPoints->GetPointAll(coords);
But I believe the compiler is free to add padding to the struct,

Not in this case.

Why not?

While definitely it could add it and be ok with the standard, it would
be strange to find an architecture+compiler where it doesnt exist k?N
such that sizeof(float) = k * /machine_word_size/... and no sensible
compiler would add padding in that case, would it? Still, we can make
soure we detect such a problem statically with a static_assert<sizeof
(Point3d) == 3*sizeof(float)>; or one can still try to avoid the padding
with compiler intrinsics in almost any sensible compiler... (yes, not
standard compliant code still).

JP

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