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

NAME
     std::multimap::erase - std::multimap::erase

Synopsis
	iterator erase( iterator pos ); 		     (1)
	iterator erase( const_iterator pos );		     (2) (since C++11)
	iterator     erase(	iterator     first,	iterator     last     );
     (until C++11)
	iterator      erase(	  const_iterator      first,	  const_iterator
     (since C++11)
	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.
	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 multimap:

	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 <map>
      #include <iostream>

      int main()
      {
	  std::multimap<int, std::string> c =
	  {
	      {1, "one"}, {2, "two"}, {3, "three"},
	      {4, "four"}, {5, "five"}, {6, "six"}
	  };

	  // erase all odd numbers from c
	  for (auto it = c.begin(); it != c.end();)
	  {
	      if (it->first % 2 != 0)
		  it = c.erase(it);
	      else
		  ++it;
	  }

	  for (auto& p : c)
	      std::cout << p.second << ' ';
	  std::cout << '\n';
      }

Output:
      two four six

       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::multimap::erase(3)
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