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

NAME
       std::multimap::key_comp - std::multimap::key_comp

Synopsis
	  key_compare key_comp() const;

	  Returns  the function	object that compares the keys, which is	a copy
       of this
	  container's constructor argument comp.

Parameters
	  (none)

Return value
	  The key comparison function object.

Complexity
	  Constant.

Example
       // Run this code

	#include <cassert>
	#include <iostream>
	#include <map>

	// Example module 97 key compare function
	struct ModCmp {
	    bool operator()(const int lhs, const int rhs) const
	    {
		return (lhs % 97) < (rhs % 97);
	    }
	};

	int main()
	{
	    std::multimap<int, char, ModCmp> cont;
	    cont = { { 1, 'a' }, { 2, 'b' }, { 3, 'c' }, { 4, 'd' }, { 5,  'e'
       } };

	    auto comp_func = cont.key_comp();

	    for	(auto it : cont) {
		bool before = comp_func(it.first, 100);
		bool after = comp_func(100, it.first);

		std::cout << '(' << it.first <<	',' << it.second;
		if (!before && !after)
		    std::cout << ") equivalent to key 100\n";
		else if	(before)
		    std::cout << ") goes before	key 100\n";
		else if	(after)
		    std::cout << ") goes after key 100\n";
		else
		    assert(0); // Cannot happen
	    }
	}

Output:
	(1,a) goes before key 100
	(2,b) goes before key 100
	(3,c) equivalent to key	100
	(4,d) goes after key 100
	(5,e) goes after key 100

See also
	  value_comp  returns  the  function  that compares keys in objects of
       type value_type
		     (public member function)

http://cppreference.com		  2022.07.31	    std::multimap::key_comp(3)

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