NAME¶

std::vector::erase - std::vector::erase

Synopsis¶

iterator erase( iterator pos ); (until C++11)
(since C++11)
iterator erase( const_iterator pos ); (constexpr since
C++20)
iterator erase( iterator first, iterator (1) (until C++11)
last );
iterator erase( const_iterator first, (2) (since C++11)
const_iterator last ); (constexpr since
C++20)

Erases the specified elements from the container.

1) Removes the element at pos.
2) Removes the elements in the range [first, last).

Iterators (including the end() iterator) and references to the elements at or after
the point of the erase are invalidated.

The iterator pos must be valid and dereferenceable. Thus the end() iterator (which
is valid, but is not dereferenceable) cannot be used as a value for pos.

The iterator first does not need to be dereferenceable if first == last: erasing an
empty range is a no-op.

Parameters¶

pos - iterator to the element to remove
first, last - range of elements to remove

Type requirements¶

-
T must meet the requirements of MoveAssignable.

Return value¶

Iterator following the last removed element.

1) If pos refers to the last element, then the end() iterator is returned.
2) If last == end() prior to removal, then the updated end() iterator is returned.
If [first, last) is an empty range, then last is returned.

Exceptions¶

Does not throw unless an exception is thrown by the assignment operator of T.

Complexity¶

Linear: the number of calls to the destructor of T is the same as the number of
elements erased, the assignment operator of T is called the number of times equal to
the number of elements in the vector after the erased elements.

Notes¶

When container elements need to be erased based on a predicate, rather than
iterating the container and calling unary erase, the iterator range overload is
generally used with std::remove()/std::remove_if() to minimise the number of moves
of the remaining (non-removed) elements, this is the erase-remove idiom.
std::erase_if() replaces the erase-remove idiom.
(since C++20)

Example¶

// Run this code

#include <vector>
#include <iostream>

void print_container(const std::vector<int>& c)
{
for (int i : c)
std::cout << i << ' ';
std::cout << '\n';
}

int main()
{
std::vector<int> c{0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
print_container(c);

c.erase(c.begin());
print_container(c);

c.erase(c.begin() + 2, c.begin() + 5);
print_container(c);

// Erase all even numbers
for (std::vector<int>::iterator it = c.begin(); it != c.end();)
{
if (*it % 2 == 0)
it = c.erase(it);
else
++it;
}
print_container(c);
}

Output:¶

0 1 2 3 4 5 6 7 8 9
1 2 3 4 5 6 7 8 9
1 2 6 7 8 9
1 7 9

Defect reports

The following behavior-changing defect reports were applied retroactively to
previously published C++ standards.

DR Applied to Behavior as published Correct behavior
first was required to be
LWG 151 C++98 dereferenceable, which not required if
made the behavior of clearing an empty first == last
vector undefined
LWG 414 C++98 iterators at the point of erase were they are also invalidated
not invalidated

See also¶

erase(std::vector) erases all elements satisfying specific criteria
erase_if(std::vector) (function template)
(C++20)
clear clears the contents
(public member function)