std::map<Key,T,Compare,Allocator>::erase

 

C++

Language

Standard Library Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

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)

Atomic operations library (C++11)

Thread support library (C++11)

Technical Specifications

 

Containers library

Sequence

array (C++11)

vector

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

Views

span (C++20)

 

std::map

Member functions

map::map

map::~map

map::operator=

map::get_allocator

Element access

map::at

map::operator[]

Iterators

map::beginmap::cbegin (C++11)

map::endmap::cend (C++11)

map::rbeginmap::crbegin (C++11)

map::rendmap::crend (C++11)

Capacity

map::empty

map::size

map::max_size

Modifiers

map::clear

map::insert

map::insert_or_assign (C++17)

map::emplace (C++11)

map::emplace_hint (C++11)

map::try_emplace (C++17)

map::erase

map::swap

map::extract (C++17)

map::merge (C++17)

Lookup

map::count

map::find

map::contains (C++20)

map::equal_range

map::lower_bound

map::upper_bound

Observers

map::key_comp

map::value_comp

Non-member functions

std::swap

erase_if (C++20)

operator==operator!=operator<operator>operator<=operator>=operator<=> (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20)

Deduction guides (C++17)

 

	(1)
void erase( iterator pos );			(until C++11)
iterator erase( const_iterator pos );			(since C++11)
iterator erase( iterator pos );			(since C++17)
		(2)
void erase( iterator first, iterator last );				(until C++11)
iterator erase( const_iterator first, const_iterator last );				(since C++11)
size_type erase( const key_type& key );			(3)

Removes specified elements from the container.

1) Removes the element at pos.

2) Removes the elements in the range [first; last), which must be a valid range in *this.

3) Removes the element (if one exists) with the key equivalent to key.

References and iterators to the erased elements are invalidated. Other references and iterators are not affected.

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.

Parameters

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

Return value

1-2) Iterator following the last removed element.

3) Number of elements removed (0 or 1).

Exceptions

1,2) Throws nothing.

3) Any exceptions thrown by the Compare object.

Complexity

Given an instance c of map:

1) Amortized constant

2) log(c.size()) + std::distance(first, last)

3) log(c.size()) + c.count(key)

Example

Run this code

#include <map>
#include <iostream>
int main()
{
    std::map<int, std::string> c = {
        {1, "one" }, {2, "two" }, {3, "three"},
        {4, "four"}, {5, "five"}, {6, "six"  }
    };
 
    // erase all odd numbers from c
    for(auto it = c.begin(); it != c.end(); ) {
        if(it->first % 2 != 0)
            it = c.erase(it);
        else
            ++it;
    }
 
    for(auto& p : c) {
        std::cout << p.second << ' ';
    }
}

Output:

two four six

See also

clear

clears the contents (public member function)