Delete of objects whose pointers are stored in an array

[nembo kid]

I have these classes:

Boss,
CommissionWorker,
PieceWorker,
HourlyWorker

all directly derived from Employeer.

I create a dynamic object (on heap) for each class:

////////////////////////////////////////////////////////////////////

Boss* b = new Boss( "Whites", "Frank", 5, 7, 1971, 1, 9, 1994, 1300);

CommissionWorker* c = new CommissionWorker("Reds", "Tom", 1, 2, 1980, 4,
5, 2001, 100, 1000, 2/100 );

PieceWorker* p = new PieceWorker( "Greens", "Bob", 24, 2, 1978, 4, 5,
2001, 10, 100 );

HourlyWorker* h = new HourlyWorker ("Blacks", "Mike", 12, 3, 1967, 13,
4, 2008, 20, 123 );

////////////////////////////////////////////////////////////////////
Then I "put" this pointers into a array of pointer to base class ( so to
upcast ):

////////////////////////////////////////////////////////////////////
Employeer* E[ 4 ] = { b, c, p, h };

////////////////////////////////////////////////////////////////////

After, I want to delete these objects from heap, with delete.

How I can do as simple as possible?
Is it correct following?

////////////////////////////////////////////////////////////////////

for ( int i = 0; i < 4; i++ ) {
delete *( E+i ) ;
}

[Victor Bazarov]

nembo kid wrote:

I have these classes:

Boss,
CommissionWorker,
PieceWorker,
HourlyWorker

all directly derived from Employeer.

I create a dynamic object (on heap) for each class:

////////////////////////////////////////////////////////////////////

Boss* b = new Boss( "Whites", "Frank", 5, 7, 1971, 1, 9, 1994, 1300);

CommissionWorker* c = new CommissionWorker("Reds", "Tom", 1, 2, 1980, 4,
5, 2001, 100, 1000, 2/100 );

PieceWorker* p = new PieceWorker( "Greens", "Bob", 24, 2, 1978, 4, 5,
2001, 10, 100 );

HourlyWorker* h = new HourlyWorker ("Blacks", "Mike", 12, 3, 1967, 13,
4, 2008, 20, 123 );

////////////////////////////////////////////////////////////////////
Then I "put" this pointers into a array of pointer to base class ( so to
upcast ):

////////////////////////////////////////////////////////////////////
Employeer* E[ 4 ] = { b, c, p, h };

////////////////////////////////////////////////////////////////////

After, I want to delete these objects from heap, with delete.

How I can do as simple as possible?
Is it correct following?

Yep.

>
////////////////////////////////////////////////////////////////////

for ( int i = 0; i < 4; i++ ) {
delete *( E+i ) ;

I would write

delete E[i];

but that's actually equivalent to what you wrote, so it's a question of
style and readability, not the functionality.

}

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[nembo kid]

Victor Bazarov ha scritto:

but that's actually equivalent to what you wrote, so it's a question of
style and readability, not the functionality.

Thanks.

[Puppet_Sock]

On Aug 7, 12:26*pm, Victor Bazarov <[e-mail]:

nembo kid wrote:

[snippers]

How I can do as simple as possible?
Is it correct following?

Yep.

[snips]

As long as the OP remembers this.

http://www.parashift.com/c++-faq-lit....html#faq-20.7

While the OP is there, it would not be a bad idea to
browse other parts of the FAQ.
Socks

[Victor Bazarov]

Puppet_Sock wrote:

On Aug 7, 12:26 pm, Victor Bazarov <[e-mail]:

>nembo kid wrote:

[snippers]

>>How I can do as simple as possible?
Is it correct following?

Yep.

[snips]

As long as the OP remembers this.

http://www.parashift.com/c++-faq-lit....html#faq-20.7

Absolutely. As soon as pressed the 'Send' button, I thought I ought to
add that... I just assume that the parts that are not shown are correct
in cases when the program is "working", and contain unknown number of
errors in cases when the program isn't.

>
While the OP is there, it would not be a bad idea to
browse other parts of the FAQ.
Socks

Second that!

V
--
Please remove capital 'A's when replying by e-mail
I do not respond to top-posted replies, please don't ask

[mlimber]

On Aug 7, 12:14*pm, nembo kid <nembo@kidwrote:
[snip]

After, I want to delete these objects from heap, with delete.

How I can do as simple as possible?

[snip]

"As simple as possible" is to rely on a smart pointer class (e.g.,
std::tr1::shared_ptr aka boost::shared_ptr) to do it for you. Then you
don't have to worry about deletion at all, and you are secure in the
face of premature exits from the relevant scope (e.g. return or an
exception) which could leave you with a memory leak. Indeed, it's a
good idea to use such RAII techniques (cf. http://www.research.att.com/~bs/bs_faq2.html#finally)
to manage all resources (see _C++ Coding Standards_ by Sutter and
Alexandrescu).

You could also use a smart pointer like the ones discussed in this FAQ
and following:

http://www.parashift.com/c++-faq-lit...html#faq-16.22

Or like the one presented in this chapter from _Modern C++ Design_ by
Alexandrescu:

http://www.informit.com/articles/art...seqNum=1&rll=1

whose most updated source can be found here:

http://loki-lib.sourceforge.net/

Cheers! --M

[Tonni Tielens]

On Aug 7, 6:14*pm, nembo kid <nembo@kidwrote:

I have these classes:

Boss,
CommissionWorker,
PieceWorker,
HourlyWorker

all directly derived from Employeer.

I create a dynamic object (on heap) for each class:

////////////////////////////////////////////////////////////////////

Boss* b = new Boss( "Whites", "Frank", 5, 7, 1971, 1, 9, 1994, 1300);

CommissionWorker* c = new CommissionWorker("Reds", "Tom", 1, 2, 1980, 4,
5, 2001, 100, 1000, 2/100 );

PieceWorker* p = new PieceWorker( "Greens", "Bob", 24, 2, 1978, 4, 5,
2001, 10, 100 );

HourlyWorker* h = new HourlyWorker ("Blacks", "Mike", 12, 3, 1967, 13,
4, 2008, 20, 123 );

////////////////////////////////////////////////////////////////////

Then I "put" this pointers into a array of pointer to base class ( so to
upcast ):

////////////////////////////////////////////////////////////////////

Employeer* E[ 4 ] = { b, c, p, h };

////////////////////////////////////////////////////////////////////

After, I want to delete these objects from heap, with delete.

How I can do as simple as possible?
Is it correct following?

////////////////////////////////////////////////////////////////////

for ( int i = 0; i < 4; i++ ) {
* * * *delete *( E+i ) ;

}

A little bit off topic, but I would also recommend using a higher form
of abstraction instead of C-style arrays. Just use a std::vector. It's
nearly as fast as an array, is compatible with C code requesting
arrays and it is far more readable and easy to use. Together with the
STL algorithms and the DeleteObject template function class (mentioned
in Scott Meyers Effective STL), vectors holding pointers to dynamic
allocated memory, can be nicely cleaned up like this.

std::vector<Employeer*e;
e.push_back(b);
e.push_back(c);
e.push_back(p);
e.push_back(h);

std::for_each(e.begin(), e.end(), DeleteObject<Employeer>());

Ofcourse the deletion would be obsolete if you would store shared_ptr
objects instead of raw pointers, already mentioned by mlimber.