std::erase, std::erase_if (std::vector)
Defined in header <vector> |
||
|---|---|---|
template< class T, class Alloc, class U >
constexpr typename std::vector<T,Alloc>::size_type
erase(std::vector<T,Alloc>& c, const U& value); |
(1) | (since C++20) |
template< class T, class Alloc, class Pred >
constexpr typename std::vector<T,Alloc>::size_type
erase_if(std::vector<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 |
Return value
The number of erased elements.
Complexity
Linear.
Example
#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 << 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 5 even numbers were erased.
See also
| removes elements satisfying specific criteria (function template) |
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https://en.cppreference.com/w/cpp/container/vector/erase2
