auto_ptr

[Sully]

Hey All,

Can someone tell me what the advantages/disadvantages are for using auto_ptr?

Thanks in advance.

[wey97]

Memory management.

The memory allocated by the new operator is deallocated as soon
as the pointer goes out of scope rather than you having to
remember/forget to deallocate using delete. In other words,
you don't have to remember to call delete. I'm sure there may be
other advantages but that's a start.

If you don't call delete when the pointer isn't needed anymore,
the app leaks memory and won't deallocate it until the app ends.

[wey97]

void function()
{
	int *n = new int(1);
	// use n
	// should call delete when finished
	// delete n;
}

int main()
{
	function();
	// if you forget to call delete in function() then
	// the memory is leaked until main is finished
}

#include <memory>

void function()
{
	std::auto_ptr<int> n(new int(1));
	// no need to call delete
	// the memory is deallocated after function
}

int main()
{
	function();
}

[Sully]

Thanks for the reply wey97...any disadvantages?

[wey97]

Your application will be bigger and it may run slightly slower but
it's unnoticeable. You have to understand how to USE auto_ptr

...but the advantages outweigh the disadvantages by a long shot.

There's been a lot of discussion about smart pointers that I've
really just now started to look in to. You may want to read up on
the concepts.

http://ootips.org/yonat/4dev/smart-pointers.html

[avaneesh]

Hi friend,

A good question raised!!!!

auto_ptr is a "smart pointer". It has advantages of small pointer
in memory management.
1. It do initialisation to NULL, deletes automatically.

2. It overloads to operators "*" & "->".

Problem like "Dangling pointers" dont appear because of that.
Its advisable to use it.
on Internet lots of inform. abt smart pointer available.

Bye.

[Sully]

Thanks to you both

And wey97, thanks for the link, I checked it out and found it very informable...

[CornedBee]

A good compiler removes any speed or size disadvantage of simple smart pointers (such as auto_ptr) vs. careful pointer code.