Re: std::list remove element mid iteration

From:

"cgspwei@gmail.com" <cgspwei@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Thu, 20 Dec 2007 03:40:16 -0800 (PST)

Message-ID:

<dcfc5f34-ab83-4db1-b22b-a30b601ebc9f@s12g2000prg.googlegroups.com>

On 12=D4 20=C8=D5, =CF =CE=E75=CA=B140=B7=D6, James Kanze <james.ka...@g=
mail.com> wrote:

On Dec 20, 2:10 am, red floyd <no.s...@here.dude> wrote:

Christopher wrote:

The situation is that a std::list<std::set<std::string> > is being
iterated through. Upon certain criteria some sets become empty. I need=

to remove the empty sets from the list.
Is it safe to iterate through a list and call list::erase( iterator )
in mid iteration?

Well, you can use
struct set_is_empty
{
bool operator()(const std::set& s) const { return s.empty(); }
};
std::erase(std::remove_if(l.begin(), l.end(), set_is_empty());

Which could be unnecessarily expensive. In the case of
std::list, the canonical form is:

l.remove_if( set_is_empty() ) ;

That is what I found in MSDN,
remove_if is a STL algorithm which removes all elements from the range
(First,Last) that cause the predicate to return true. It returns an
iterator equal to Last - n, where n = number of elements removed. The
last n elements of the range have undefined values. The size of the
container remains the same.
But there is a method named remove_if in std::list.
template<class Predicate>
void remove_if(
Predicate _Pred
)
Erases elements from a list for which a specified predicate is
satisfied.
I didn't know there is a method named remove_if in the std::list. Can
any one told me why there is no similar method in vector ?

Thanks in advance,:)