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void erase ( iterator position );
size_type erase ( const key_type& x );
void erase ( iterator first, iterator last );
Erase elements
Removes elements from the container.
This effectively reduces the container size by the number of elements removed, calling each element's destructor before.
The version and parameters used determine the elements removed:
Parameters
- position
- Iterator pointing to a single element to be removed from the container.
iterator is a member type, defined as a bidirectional iterator type.
- x
- Value of the elements to be removed from the container. All the elements with this value are removed.
key_type is a member type defined in multiset containers as an alias of Key, which is the first template parameter and the type of the elements stored in the container.
- first, last
- Iterators specifying a range within the container to be removed: [first,last). i.e., the range includes all the elements between first and last, including the element pointed by first but not the one pointed by last.
Return value
Only for the second version, the function returns the number of elements erased (which may be zero if x does not match any element in the container).
Example
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// erasing from multiset
#include <iostream>
#include <set>
using namespace std;
int main ()
{
multiset<int> mymultiset;
multiset<int>::iterator it;
// insert some values:
mymultiset.insert (40); // 40
for (int i=1; i<7; i++) mymultiset.insert(i*10); // 10 20 30 40 40 50 60
it=mymultiset.begin();
it++; // ^
mymultiset.erase (it); // 10 30 40 40 50 60
mymultiset.erase (40); // 10 30 50 60
it=mymultiset.find (50);
mymultiset.erase ( it, mymultiset.end() ); // 10 30
cout << "mymultiset contains:";
for (it=mymultiset.begin(); it!=mymultiset.end(); ++it)
cout << " " << *it;
cout << endl;
return 0;
}
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Output:
mymultiset contains: 10 30
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Complexity
For the first version ( erase(position) ), amortized constant.
For the second version ( erase(x) ), logarithmic in container size plus linear in number of element removed (destructors).
For the last version ( erase(first,last) ), logarithmic in container size plus linear in the distance between first and last.
See also
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