std::erase, std::erase_if (std::vector)
From cppreference.com
Defined in header <vector>
|
||
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 (char x : c) std::cout << x << ' '; std::cout << "}\n"; } int main() { std::vector<char> cnt(10); std::iota(cnt.begin(), cnt.end(), '0'); print_container("Initially, cnt = ", cnt); std::erase(cnt, '3'); print_container("After erase '3', cnt = ", cnt); auto erased = std::erase_if(cnt, [](char x) { return (x - '0') % 2 == 0; }); print_container("After erase all even numbers, cnt = ", cnt); std::cout << "Erased even numbers: " << erased << '\n'; }
Output:
Initially, cnt = { 0 1 2 3 4 5 6 7 8 9 } After erase '3', cnt = { 0 1 2 4 5 6 7 8 9 } After erase all even numbers, cnt = { 1 5 7 9 } Erased even numbers: 5
See also
removes elements satisfying specific criteria (function template) |