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std::deque::erase(3) C++ Standard Libary std::deque::erase(3) NAME std::deque::erase - std::deque::erase Synopsis iterator erase( iterator pos ); (until C++11) iterator erase( const_iterator pos ); (since C++11) iterator erase( iterator first, iterator last ); (1) (until C++11) iterator erase( const_iterator first, (2) (since C++11) const_iterator last ); Erases the specified elements from the container. 1) Removes the element at pos. 2) Removes the elements in the range [first, last). All iterators and references are invalidated, unless the erased ele- ments are at the end or at the beginning of the container, in which case only the it- erators and references to the erased elements are invalidated. The end() itera- tor is also invalidated unless the erased elements are at the beginning of the container and the last element is not erased. The iterator pos must be valid and dereferenceable. Thus the end() iterator (which is valid, but is not dereferenceable) cannot be used as a value for pos. The iterator first does not need to be dereferenceable if first == last: erasing an empty range is a no-op. Parameters pos - iterator to the element to remove first, last - range of elements to remove Type requirements - T must meet the requirements of MoveAssignable. Return value Iterator following the last removed element. 1) If pos refers to the last element, then the end() iterator is re- turned. 2) If last == end() prior to removal, then the updated end() itera- tor is returned. If [first, last) is an empty range, then last is returned. Exceptions Does not throw unless an exception is thrown by the assignment oper- ator of T. Complexity Linear: the number of calls to the destructor of T is the same as the number of elements erased, the number of calls to the assignment operator of T is no more than the lesser of the number of elements before the erased elements and the number of elements after the erased elements. Notes When container elements need to be erased based on a predicate, rather than iterating the container and calling unary erase, the iterator range overload is generally used with std::remove()/std::remove_if() to minimise the number of moves of the remaining (non-removed) elements, this is the erase-remove idiom. std::erase_if() replaces the erase-remove idiom. (since C++20) Example // Run this code #include <deque> #include <iostream> void print_container(const std::deque<int>& c) { for (int i : c) std::cout << i << ' '; std::cout << '\n'; } int main() { std::deque<int> c{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}; print_container(c); c.erase(c.begin()); print_container(c); c.erase(c.begin() + 2, c.begin() + 5); print_container(c); // Erase all even numbers for (std::deque<int>::iterator it = c.begin(); it != c.end();) { if (*it % 2 == 0) it = c.erase(it); else ++it; } print_container(c); } Output: 0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 6 7 8 9 1 7 9 Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Cor- rect behavior first was required to be LWG 151 C++98 dereferenceable, which not re- quired if made the behavior of clearing an empty first == last deque undefined it is in- validated if the LWG 638 C++98 the past-the-end iterator was not elements are invalidated erased from the middle or the end See also erase(std::deque) erases all elements satisfying specific crite- ria erase_if(std::deque) (function template) (C++20) clear clears the contents (public member function) http://cppreference.com 2024.06.10 std::deque::erase(3)
NAME | Synopsis | Parameters | Type requirements | Return value | Exceptions | Complexity | Notes | Example | Output: | See also
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