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std::multiset::erase(3)        C++ Standard Libary	 std::multiset::erase(3)

NAME
     std::multiset::erase - std::multiset::erase

Synopsis
	iterator erase( iterator pos ); 			 (until C++23)
	iterator erase( iterator pos )
	    requires(!std::same_as<iterator,			 (since C++23)
	const_iterator>);
	iterator erase( const_iterator pos );		     (2) (since C++11)
	iterator    erase(    iterator	  first,    iterator	last	);   (1)
     (until C++11)
	iterator	    erase(	       const_iterator		  first,
     (since C++11)
	const_iterator last );				     (3)
	size_type erase( const Key& key );			 (4)
	template<    class    K    >					     (5)
     (since C++23)
	size_type erase( K&& x );

	Removes specified elements from the container. The order of the  remain-
     ing equivalent
	elements is preserved.

	1,2) Removes the element at pos.
	Only  one  overload  is  provided if iterator and const_iterator are the
     same type.
	(since C++11)
	3) Removes the elements in the range [first,  last),  which  must  be  a
     valid range in
	*this.
	4) Removes all elements with the key equivalent to key.
	5)  Removes  all elements with key that compares equivalent to the value
     x. This
	overload participates in overload resolution only if the qualified-id
	Compare::is_transparent is valid and denotes a type, and neither  itera-
     tor nor
	const_iterator	is implicitly convertible from K. It allows calling this
     function
	without constructing an instance of Key.

	References and iterators to the erased elements are  invalidated.  Other
     references
	and iterators are not affected.

	The iterator pos must be valid and dereferenceable. Thus the end() iter-
     ator (which
	is valid, but is not dereferenceable) cannot be used as a value for pos.

Parameters
	pos	    - iterator to the element to remove
	first, last - range of elements to remove
	key	    - key value of the elements to remove
	x	     -	a  value  of any type that can be transparently compared
     with a key
		      denoting the elements to remove

Return value
	1-3) Iterator following the last removed element.
	4) Number of elements removed.
	5) Number of elements removed.

Exceptions
	1-3) Throws nothing.
	4,5) Any exceptions thrown by the Compare object.

Complexity
	Given an instance c of multiset:

	1,2) Amortized constant
	3) log(c.size()) + std::distance(first, last)
	4) log(c.size()) + c.count(key)
	5) log(c.size()) + c.count(x)

Notes
		    Feature-test macro		     Value    Std	    Fea-
     ture
								    Heteroge-
     neous erasure in
								    associative
     containers
	__cpp_lib_associative_heterogeneous_erasure  202110L  (C++23)  and   un-
     ordered
								    associative
     containers;
								    overload (5)

Example
     // Run this code

      #include <set>
      #include <iostream>

      int main()
      {
	  std::multiset<int> c = {1, 2, 3, 4, 1, 2, 3, 4};

	  auto print = [&c]
	  {
	      std::cout << "c = { ";
	      for (int n : c)
		  std::cout << n << ' ';
	      std::cout << "}\n";
	  };
	  print();

	  std::cout << "Erase all odd numbers:\n";
	  for (auto it = c.begin(); it != c.end();)
	  {
	      if (*it % 2 != 0)
		  it = c.erase(it);
	      else
		  ++it;
	  }
	  print();

	  std::cout << "Erase 1, erased count: " << c.erase(1) << '\n';
	  std::cout << "Erase 2, erased count: " << c.erase(2) << '\n';
	  std::cout << "Erase 2, erased count: " << c.erase(2) << '\n';
	  print();
      }

       Defect reports

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

	   DR	 Applied to	     Behavior as published		 Correct
     behavior
			    the return type of overloads (1) and (3)
	LWG  130   C++98      was void (it is not		       corrected
     to iterator
			    consistent with the erase() requirement
			    on sequence containers)
			    the order of equivalent elements that
	LWG 371  C++98	    are not				     required to
     be
			    erased was not guaranteed to be	     preserved
			    preserved
	LWG 2059 C++11	    replacing overload (1) with overload (2) added over-
     load (1) back
			    introduced new ambiguity

See also
	clear clears the contents
	      (public member function)

http://cppreference.com 	   2024.06.10		 std::multiset::erase(3)
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