how can I loop a std::list ?

[Joseph]

Hi guys,

i have a list which have some objects in it

and I want to find a specific one and delete that,I thought that it could
be done with iterator like
//=======fake code==============
for(iteratorA=list.begin();iteratorA<list.end();++ iteratorA)

//======================

but I failed,is there any way loop through the list (without pop
anything,list stays same)?

Thanks a lot!!

[Siemel Naran]

"Joseph" <wu*******@hotmail.com> wrote in message

for(iteratorA=list.begin();iteratorA<list.end();++ iteratorA)

There is no operator< for pretty much all iterators. It would be too
expensive to implement for a list. Use != instead.

for(iteratorA=list.begin();iteratorA!=list.end();+ +iteratorA) {
cout << *iteratorA;
}

As for removing an element from a list, you can use the member functions
list::remove or list::remove_if.

Please be aware that the following does not work, and can you tell why?

for(iteratorA=list.begin();iteratorA!=list.end();+ +iteratorA) {
if (*iteratorA == 3) list.erase(iteratorA);
}

[Carlos Martinez Garcia]

Iterators are a good option. Probably you have made some mistake in your
code.

What's the iterator's object declaration?
What's the error you get?

Joseph escribió:

Hi guys,

i have a list which have some objects in it

and I want to find a specific one and delete that,I thought that it could
be done with iterator like
//=======fake code==============
for(iteratorA=list.begin();iteratorA<list.end();++ iteratorA)

//======================

but I failed,is there any way loop through the list (without pop
anything,list stays same)?

Thanks a lot!!

[Joseph]

Carlos Martinez Garcia <cm****@tid.es> wrote in
news:cf*********@news.hi.inet:

Iterators are a good option. Probably you have made some mistake in
your code.

What's the iterator's object declaration?
What's the error you get?

Joseph escribi?

Hi guys,

i have a list which have some objects in it

and I want to find a specific one and delete that,I thought that it
could be done with iterator like
//=======fake code==============
for(iteratorA=list.begin();iteratorA<list.end();++ iteratorA)

//======================

but I failed,is there any way loop through the list (without pop
anything,list stays same)?

Thanks a lot!!

Hi Carlos,

the error is exactlly like Siemel said(no "<" operator),so ,I would use !=
instead.

cheers!

[David Ecker]

Siemel Naran wrote:

"Joseph" <wu*******@hotmail.com> wrote in message

for(iteratorA=list.begin();iteratorA<list.end();++ iteratorA)

There is no operator< for pretty much all iterators. It would be too
expensive to implement for a list. Use != instead.

for(iteratorA=list.begin();iteratorA!=list.end();+ +iteratorA) {
cout << *iteratorA;
}

As for removing an element from a list, you can use the member functions
list::remove or list::remove_if.

Please be aware that the following does not work, and can you tell why?

for(iteratorA=list.begin();iteratorA!=list.end();+ +iteratorA) {
if (*iteratorA == 3) list.erase(iteratorA);
}

Of course, the iterator is invalid after the erase. It points to a delete
item.

by
David

[jota]

> and I want to find a specific one and delete that,I thought that it could

be done with iterator like

I have done something like that and here is the idea!
I make a copy of the list with all the items to be deleted!
Since there is alot of selections to be considered I found that
this way give me a good readibility!
The destructor of the object removes and deletes it self from the static
main list!
Ofcourse LIST is a typedef of my objects!
{
LIST l;
std::copy_if(List.begin(),List.end(),std::back_ins erter(l),pred1);
std::copy_if(List.begin(),List.end(),std::back_ins erter(l),pred2);
for(LIST::iterator i=l.begin();i!=l.end();i++)
delete (*i);
}

//jota

[Siemel Naran]

"David Ecker" <da***@familie-ecker.net> wrote in message news:D4GSc.2784

Siemel Naran wrote:

Please be aware that the following does not work, and can you tell why?

for(iteratorA=list.begin();iteratorA!=list.end();+ +iteratorA) {
if (*iteratorA == 3) list.erase(iteratorA);
}

Of course, the iterator is invalid after the erase. It points to a delete
item.

Right. So do you know how to fix it (assuming you don't want to use
list::remove or are implementing this function)?