Suppose I have
vector<intvi;
deque<intdi;
list<intli;
Suppose all of these containers have some elements.
Suppose 'v_iter' is an iterator pointing to some element in 'vi'.
Suppose 'v_beg' and 'v_end' are valid iterators pointing to some
elements in 'vi' itself; but 'v_iter' does not fall in the range
[v_begin, v_end).
Then the operation vi.insert(v_ite r, v_beg, v_end) is INVALID because
v_beg and v_end may be invalidated after the insertion of the first
element in the range [v_begin, v_end).
Same reason applies to deque for the same operation di.insert(d_ite r,
d_beg, d_end);
Is my above understanding correct ?
However, suppose 'l_iter' is an iterator pointing to some element in
'li'. Suppose 'l_beg' and 'l_end' are valid iterators pointing to some
elements in 'li' itself; but 'l_iter' does not fall in the range
[l_begin, l_end).
Then, the operation li.insert(l_ite r, l_beg, l_end) is valid because
for a list, by the way of insertion, the iterators l_beg and l_end are
not invalidated for list.
Is this reason correct?
Kindly clarify.
Thanks
V.Subramanian
1  2538  su************* *@yahoo.com, India wrote:
Suppose I have
vector<intvi;
deque<intdi;
list<intli;
Suppose all of these containers have some elements.
Suppose 'v_iter' is an iterator pointing to some element in 'vi'.
Suppose 'v_beg' and 'v_end' are valid iterators pointing to some
elements in 'vi' itself; but 'v_iter' does not fall in the range
[v_begin, v_end).
Then the operation vi.insert(v_ite r, v_beg, v_end) is INVALID because
v_beg and v_end may be invalidated after the insertion of the first
element in the range [v_begin, v_end).
Same reason applies to deque for the same operation di.insert(d_ite r,
d_beg, d_end);
Is my above understanding correct ?
No. The insertion is invalid because the standard states [Table 67] as a
precondition that the range arguments to insert must not be iterators into
the sequence into which you insert. Whether iterators are invalidated or
not is immaterial.
However, suppose 'l_iter' is an iterator pointing to some element in
'li'. Suppose 'l_beg' and 'l_end' are valid iterators pointing to some
elements in 'li' itself; but 'l_iter' does not fall in the range
[l_begin, l_end).
Then, the operation li.insert(l_ite r, l_beg, l_end) is valid because
for a list, by the way of insertion, the iterators l_beg and l_end are
not invalidated for list.
Is this reason correct?
I don't think so. As far as I know the precondition in Table 67 applies to
lists as well. I am not aware of additional language in the standard that
makes an exception for lists. As far as I can tell, you have undefined
behavior either way.
Best
Kai-Uwe Bux This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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