std::erase, std::erase_if (std::vector)
From cppreference.com
Defined in header <vector>
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template< class T, class Alloc, class U > constexpr typename std::vector<T,Alloc>::size_type |
(1) | (since C++20) |
template< class T, class Alloc, class Pred > constexpr typename std::vector<T,Alloc>::size_type |
(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 |
Return value
The number of erased elements.
Complexity
Linear.
Example
Run this code
#include <iostream> #include <numeric> #include <string_view> #include <vector> void print_container(std::string_view comment, const std::vector<char>& c) { std::cout << comment; for (auto x : c) { std::cout << x << ' '; } std::cout << '\n'; } int main() { std::vector<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
removes elements satisfying specific criteria (function template) |