Re: question about erase() function on a container

From:
James Kanze <james.kanze@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Sun, 3 Feb 2008 02:45:42 -0800 (PST)
Message-ID:
<37e43ba3-1ec5-4c9b-a184-8562f7be47b3@h11g2000prf.googlegroups.com>
subramanian100in@yahoo.com, India wrote:

Suppose I have

vector<int> container;

Suppose I store some values into "container".

Suppose that "left" and "right" are valid iterators into
"container" and that "right" is NOT container.end() and
"right" comes after "left".

Given this, suppose

vector<int>::iterator iter = container.erase(left, right);

then "iter" will always be a copy of "right" iterator.
ie
if (iter == right) will always be true. Am I correct ? The same is
true for deque and list also. Is this correct ?


No.

After the erase, right is invalid, and any attempt to use it
(including comparing it with iter) is undefined behavior. With
g++, in debug mode, it crashes---I would expect this to be the
case with any quality implementation.

Given a standard library container, can we call clear() function on
empty container ? Or will it invoke undefined behaviour ?


You can always call clear(), on any container.

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