std::erase, std::erase_if(std::vector) - cppreference.com (original) (raw)

Defined in header
(1)
template< class T, class Alloc, class U > constexpr typename std::vector<T, Alloc>::size_type erase( std::vector<T, Alloc>& c, const U& value );		(since C++20) (until C++26)
template< class T, class Alloc, class U = T > constexpr typename std::vector<T, Alloc>::size_type erase( std::vector<T, Alloc>& c, const U& value );		(since C++26)
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)

Erases all elements that compare equal to value from the container c.

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

Erases all elements that satisfy the predicate pred from the container c.

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

[edit] 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).

[edit] Return value

The number of erased elements.

[edit] Complexity

Linear.

Notes

Feature-test macro	Value	Std	Feature
__cpp_lib_algorithm_default_value_type	202403	(C++26)	List-initialization for std::erase

[edit] Example

#include #include #include #include #include void println(std::string_view comment, const auto& c) { std::cout << comment << '['; bool first{true}; for (const auto& x : c) std::cout << (first ? first = false, "" : ", ") << x; std::cout << "]\n"; } int main() { std::vector cnt(10); std::iota(cnt.begin(), cnt.end(), '0'); println("Initially, cnt = ", cnt); std::erase(cnt, '3'); println("After erase '3', cnt = ", cnt); auto erased = std::erase_if(cnt, [](char x) { return (x - '0') % 2 == 0; }); println("After erase all even numbers, cnt = ", cnt); std::cout << "Erased even numbers: " << erased << '\n'; std::vector<std::complex> nums{{2, 2}, {4, 2}, {4, 8}, {4, 2}}; #ifdef __cpp_lib_algorithm_default_value_type std::erase(nums, {4, 2}); #else std::erase(nums, std::complex{4, 2}); #endif println("After erase {4, 2}, nums = ", nums); }

Output: