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      std::deque<T,Allocator>::erase

      From cppreference.com
      <cpp‎ |container‎ |deque

      [edit template]
       
       
       
      std::deque
      Member types
      Member functions
      Non-member functions
      (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
      Deduction guides(C++17)
       
      (1)
      iterator erase( iterator pos);
      (until C++11)
      iterator erase( const_iterator pos);
      (since C++11)
      (constexpr since C++26)
      (2)
      iterator erase( iterator first, iterator last);
      (until C++11)
      iterator erase( const_iterator first, const_iterator last);
      (since C++11)
      (constexpr since C++26)

      Erases the specified elements from the container.

      1) Removes the element atpos.
      2) Removes the elements in the range[firstlast).

      All iterators and references are invalidated, unless the erased elements are at the end or at the beginning of the container, in which case only the iterators and references to the erased elements are invalidated. Theend() iterator is also invalidated unless the erased elements are at the beginning of the container and the last element is not erased.

      The iteratorpos must be valid and dereferenceable. Thus theend() iterator (which is valid, but is not dereferenceable) cannot be used as a value forpos.

      The iteratorfirst does not need to be dereferenceable iffirst== last: erasing an empty range is a no-op.

      Contents

      [edit]Parameters

      pos - iterator to the element to remove
      first, last - the pair of iterators defining therange of elements to remove
      Type requirements
      -
      IfT is notMoveAssignable, the behavior is undefined.

      [edit]Return value

      Iterator following the last removed element.

      1) Ifpos refers to the last element, then theend() iterator is returned.
      2) Iflast== end() prior to removal, then the updatedend() iterator is returned.
      If[firstlast) is an empty range, thenlast is returned.

      Exceptions

      Does not throw unless an exception is thrown by the assignment operator ofT.

      [edit]Complexity

      Linear: the number of calls to the destructor ofT is the same as the number of elements erased, the number of calls to the assignment operator ofT is no more than the lesser of the number of elements before the erased elements and the number of elements after the erased elements.

      [edit]Notes

      When container elements need to be erased based on a predicate, rather than iterating the container and calling unaryerase, the iterator range overload is generally used withstd::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)

      [edit]Example

      Run this code
      #include <deque>#include <iostream>  void print_container(conststd::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 numbersfor(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 91 2 3 4 5 6 7 8 91 2 6 7 8 91 7 9

      Defect reports

      The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

      DRApplied toBehavior as publishedCorrect behavior
      LWG 151C++98first was required to be dereferenceable, which
      made the behavior of clearing an emptydeque undefined
      not required if
      first== last
      LWG 638C++98the past-the-end iterator was not invalidatedit is invalidated if the elements are
      erased from the middle or the end

      [edit]See also

      erases all elements satisfying specific criteria
      (function template)[edit]
      clears the contents
      (public member function)[edit]
      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/container/deque/erase&oldid=135182"

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