std::erase, std::erase_if (std::deque)

 

C++

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Named requirements

Feature test macros (C++20)

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Concepts library (C++20)

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Ranges library (C++20)

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Technical specifications

Symbols index

External libraries

 

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::deque

Member functions

deque::deque

deque::~deque

deque::operator=

deque::assign

deque::get_allocator

Element access

deque::at

deque::operator[]

deque::front

deque::back

Iterators

deque::begindeque::cbegin (C++11)

deque::enddeque::cend (C++11)

deque::rbegindeque::crbegin (C++11)

deque::renddeque::crend (C++11)

Capacity

deque::empty

deque::size

deque::max_size

deque::shrink_to_fit

Modifiers

deque::clear

deque::insert

deque::emplace

deque::erase

deque::push_front

deque::emplace_front

deque::pop_front

deque::push_back

deque::emplace_back

deque::pop_back

deque::resize

deque::swap

Non-member functions

std::swap

eraseerase_if (C++20)(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)

 

Defined in header <deque>
template< class T, class Alloc, class U > typename std::deque<T,Alloc>::size_type     erase(std::deque<T,Alloc>& c, const U& value);	(1)	(since C++20)
template< class T, class Alloc, class Pred > typename std::deque<T,Alloc>::size_type     erase_if(std::deque<T,Alloc>& c, Pred pred);	(2)	(since C++20)

1) Erases all elements that compare equal to value from the container. Equivalent to

auto it = std::remove(c.begin(), c.end(), value);
auto r = std::distance(it, c.end());
c.erase(it, c.end());
return r;

2) Erases all elements that satisfy the predicate pred from the container. Equivalent to

auto it = std::remove_if(c.begin(), c.end(), pred);
auto r = std::distance(it, c.end());
c.erase(it, c.end());
return r;

Parameters

c	-	container from which to erase
value	-	value to be removed
pred	-	unary predicate which returns ​true if the element should be erased. The expression pred(v) must be convertible to bool for every argument v of type (possibly const) T, regardless of value category, and must not modify v. Thus, a parameter type of T&is not allowed, nor is T unless for T a move is equivalent to a copy (since C++11). ​

Return value

The number of erased elements.

Complexity

Linear.

Example

Run this code

#include <iostream>
#include <numeric>
#include <string_view>
#include <deque>
 
void print_container(std::string_view comment, const std::deque<char>& c)
{
    std::cout << comment;
    for (auto x : c) {
        std::cout << x << ' ';
    }
    std::cout << '\n';
}
 
int main()
{
    std::deque<char> cnt(10);
    std::iota(cnt.begin(), cnt.end(), '0');
    print_container("Init:\n", cnt);
 
    std::erase(cnt, '3');
    print_container("Erase '3':\n", cnt);
 
    auto erased = std::erase_if(cnt, [](char x) { return (x - '0') % 2 == 0; });
    print_container("Erase all even numbers:\n", cnt);
    std::cout << "In all " << erased << " even numbers were erased.\n";
}

Output:

Init:
0 1 2 3 4 5 6 7 8 9 
Erase '3':
0 1 2 4 5 6 7 8 9 
Erase all even numbers:
1 5 7 9
In all 5 even numbers were erased.

See also

removeremove_if

removes elements satisfying specific criteria (function template)