std::vector<T,Allocator>::erase

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support library (C++26)

Technical specifications

Symbols index

External libraries

 

Containers library

Sequence

array (C++11)

vector

vector<bool>

inplace_vector (C++26)

deque

forward_list (C++11)

list

Associative

set

multiset

map

multimap

Unordered associative

unordered_set (C++11)

unordered_multiset (C++11)

unordered_map (C++11)

unordered_multimap (C++11)

Adaptors

stack

queue

priority_queue

flat_set (C++23)

flat_multiset (C++23)

flat_map (C++23)

flat_multimap (C++23)

Views

span (C++20)

mdspan (C++23)

Tables

Iterator invalidation

Member function table

Non-member function table

 

std::vector

Member types
Member functions
vector::vector vector::~vector vector::operator= vector::assign vector::assign_range (C++23)   vector::get_allocator Element access vector::operator[] vector::at vector::data vector::front vector::back Iterators vector::beginvector::cbegin (C++11) vector::endvector::cend (C++11) vector::rbeginvector::crbegin (C++11) vector::rendvector::crend (C++11)	Capacity vector::empty vector::size vector::max_size vector::reserve vector::capacity vector::shrink_to_fit (DR*) Modifiers vector::clear vector::erase vector::insert vector::insert_range (C++23) vector::append_range (C++23) vector::emplace (C++11) vector::emplace_back (C++11) vector::push_back vector::pop_back vector::resize vector::swap
Non-member functions
operator==operator<=> (C++20) swap(std::vector) erase(std::vector)erase_if(std::vector) (C++20)(C++20)	operator!=operator<operator>operator<=operator>= (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
Deduction guides(C++17)

 

	(1)
iterator erase( iterator pos );			(until C++11)
iterator erase( const_iterator pos );			(since C++11) (constexpr since C++20)
		(2)
iterator erase( iterator first, iterator last );				(until C++11)
iterator erase( const_iterator first, const_iterator last );				(since C++11) (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
LWG 151	C++98	first was required to be dereferenceable, which made the behavior of clearing an empty vector undefined	not required if first == last
LWG 414	C++98	iterators at the point of erase were not invalidated	they are also invalidated

See also

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