Skip to main content

Operator new

In C++, if you want to mimic malloc style behavior in
pure C++ way then write

Box *b = (Box *) operator new (sizeof (Box)); // statement 1

By this I mean the constructor of Box will not be invoked
as you expect with malloc. Note that this is NOT equivalent to

Box * b = new Box; // Statement 2

because doing that invokes the constructor.

Statment 1 is know as "operator new"!!
AND
Statment 2 is know as "new operator"!!

You have to match statement 1 by
operator delete(b); // does not invoke destructor
and statement 2 by
delete b; // invokes destructor

Comments

Anonymous said…
What a nice blog you have! You can be sure that I'll be coming back!

Check my golfing blog!
Anonymous said…
October 2005
Carnival of Diasporas - no Armenians Allowed Filed under: Armenia , Diaspora , Technology - Posted by Katy on October 1st A few weeks ago I posted a link to the Carnival of Diasporas .
Hey, you have a great blog here! I'm definitely going to bookmark you!

I have a winning ad copy site/blog. It pretty much covers winning ad copy related stuff.

Come and check it out if you get time :-)
Sensational blog. I took pleasure in the site and I
will go back! Surfing online for blogs like this one
is worth my time.
Come as you are and look at my faxless cash advance blog.
Astonshing blog. I relished in the site and you
know I will be going to it again! Surfing the internet
hepls me to find blogs that arfe just as good.
It may look like it was hard work, but my 1800contacts coupon blog was simple.
Captivate blog. I surf the web for blogs this
nature.The site are wonderful and will be returned to
again!
Look who checking out my 1800contacts coupon code blog?
dat-girl said…
Unusual blog. I liked the site its from so much I
have to visit it again! I surf the web for blogs like
yours in my spare time.
Want to see top notch work, peep my 1800contacts coupon codes blog site for the bomb work!
Nice blog. I seen the site and I adored the work,
that I want to visit it more each day! I like
searching for blogs that have the same content like
this one!
Please discover my 1800contacts web coupon code blog.
lightly-blended said…
Hype blog. And I admire your site and plan on
returning to it! When I web surf it always helps me to
find great blogs.
Hey why don't you peep my 1800contacts coupon code blog site.
Great blog. I'm always finding blog like yours. It
got my attention and I will go to the site again!
Please proceed to my 1800contacts web coupon code blog when you find the time.
Exciting blog. Your site was amazing and will be
back again! I never get tired of looking for blogs
just like this one.
Please come by and see my 1800contacts coupon codes blog.
Great blog. I'm always finding blog like yours. It
got my attention and I will go to the site again!
Look into my 1800contacts coupon blog.
die4-u said…
Excellent blog.  I go though the web in search of
blogs like this one. Its so good, that I plan on
returning to its site!
Go and click my coupon codes 1800contacts blog.
Great blog. I surf the web looking for blogs like
this. Your site was on point and will be back again!
My plastic surgery illinois blog, is something you need to peep out!
I surf the web looking for blogs like this one.
Your site was on point and will be back again! Awesome
blog.
I wish I was like you, but I'll go and peep your 1800contacts web coupon code blog.

Popular posts from this blog

Multi-dimensional arrays in C++11

What new can be said about multi-dimensional arrays in C++? As it turns out, quite a bit! With the advent of C++11, we get new standard library class std::array. We also get new language features, such as template aliases and variadic templates. So I'll talk about interesting ways in which they come together.

It all started with a simple question of how to define a multi-dimensional std::array. It is a great example of deceptively simple things. Are the following the two arrays identical except that one is native and the other one is std::array?

int native[3][4];
std::array<std::array<int, 3>, 4> arr;

No! They are not. In fact, arr is more like an int[4][3]. Note the difference in the array subscripts. The native array is an array of 3 elements where every element is itself an array of 4 integers. 3 rows and 4 columns. If you want a std::array with the same layout, what you really need is:

std::array<std::array<int, 4>, 3> arr;

That's quite annoying for two r…

Inheritance vs std::variant

C++17 added std::variant and std::visit in its repertoire. They are worth a close examination. I've been wondering about whether they are always better than inheritance for modeling sum-types (fancy name for discriminated unions) and if not, under what circumstances they are not. We'll compare the two approaches in this blog post. So here it goes.

Inheritancestd::variantNeed not know all the derived types upfront (open-world assumption)Must know all the cases upfront (closed-world assumption)Dynamic Allocation (usually)No dynamic allocationIntrusive (must inherit from the base class)Non-intrusive (third-party classes can participate)Reference semantics (think how you copy a vector of pointers to base class?)Value semantics (copying is trivial)Algorithm scattered into classesAlgorithm in one placeLanguage supported (Clear errors if pure-virtual is not implemented)Library supported (poor error messages)Creates a first-class abstractionIt’s just a containerKeeps fluent interfaces…

Covariance and Contravariance in C++ Standard Library

Covariance and Contravariance are concepts that come up often as you go deeper into generic programming. While designing a language that supports parametric polymorphism (e.g., templates in C++, generics in Java, C#), the language designer has a choice between Invariance, Covariance, and Contravariance when dealing with generic types. C++'s choice is "invariance". Let's look at an example.
struct Vehicle {}; struct Car : Vehicle {}; std::vector<Vehicle *> vehicles; std::vector<Car *> cars; vehicles = cars; // Does not compile The above program does not compile because C++ templates are invariant. Of course, each time a C++ template is instantiated, the compiler creates a brand new type that uniquely represents that instantiation. Any other type to the same template creates another unique type that has nothing to do with the earlier one. Any two unrelated user-defined types in C++ can't be assigned to each-other by default. You have to provide a c…