public member function
<set>

std::set::erase

(1)
     void erase (iterator position);
(2)
size_type erase (const value_type& val);
(3)
     void erase (iterator first, iterator last);
(1)
iterator  erase (const_iterator position);
(2)
size_type erase (const value_type& val);
(3)
iterator  erase (const_iterator first, const_iterator last);
Erase elements
Removes from the set container either a single element or a range of elements ([first,last)).

This effectively reduces the container size by the number of elements removed, which are destroyed.

Parameters

position
Iterator pointing to a single element to be removed from the set.
Member types iterator and const_iterator are bidirectional iterator types that point to elements.
val
Value to be removed from the set.
Member type value_type is the type of the elements in the container, defined in set as an alias of its first template parameter (T).
first, last
Iterators specifying a range within the set 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.
Member types iterator and const_iterator are bidirectional iterator types that point to elements.

Return value

For the value-based version (2), the function returns the number of elements erased.

Member type size_type is an unsigned integral type.

The other versions return no value.
The other versions return an iterator to the element that follows the last element removed (or set::end, if the last element was removed).

Member type iterator is a bidirectional iterator type that points to elements.

Example

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// erasing from set
#include <iostream>
#include <set>

int main ()
{
  std::set<int> myset;
  std::set<int>::iterator it;

  // insert some values:
  for (int i=1; i<10; i++) myset.insert(i*10);  // 10 20 30 40 50 60 70 80 90

  it = myset.begin();
  ++it;                                         // "it" points now to 20

  myset.erase (it);

  myset.erase (40);

  it = myset.find (60);
  myset.erase (it, myset.end());

  std::cout << "myset contains:";
  for (it=myset.begin(); it!=myset.end(); ++it)
    std::cout << ' ' << *it;
  std::cout << '\n';

  return 0;
}

Output:
myset contains: 10 30 50

Complexity

For the first version (erase(position)), amortized constant.
For the second version (erase(val)), logarithmic in container size.
For the last version (erase(first,last)), linear in the distance between first and last.

Iterator validity

Iterators, pointers and references referring to elements removed by the function are invalidated.
All other iterators, pointers and references keep their validity.

Data races

The container is modified.
The elements removed are modified. Concurrently accessing other elements is safe, although iterating ranges in the container is not.

Exception safety

Unless the container's comparison object throws, this function never throws exceptions (no-throw guarantee).
Otherwise, if a single element is to be removed, there are no changes in the container in case of exception (strong guarantee).
Otherwise, the container is guaranteed to end in a valid state (basic guarantee).
If an invalid position or range is specified, it causes undefined behavior.

See also

  • 997351548 2018-02-20
  • 903691547 2018-02-20
  • 9127171546 2018-02-20
  • 2234751545 2018-02-20
  • 1685381544 2018-02-20
  • 911091543 2018-02-20
  • 9281021542 2018-02-20
  • 632231541 2018-02-20
  • 9751491540 2018-02-20
  • 8333621539 2018-02-20
  • 995001538 2018-02-20
  • 6477441537 2018-02-20
  • 511981536 2018-02-19
  • 2072881535 2018-02-19
  • 6024461534 2018-02-19
  • 7594061533 2018-02-19
  • 9311341532 2018-02-19
  • 4928331531 2018-02-19
  • 38561530 2018-02-19
  • 7776611529 2018-02-19