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std::flat_set::value_comp(3)   C++ Standard Libary  std::flat_set::value_comp(3)

NAME
     std::flat_set::value_comp - std::flat_set::value_comp

Synopsis
	std::flat_set::value_compare value_comp() const;  (since C++23)

	Returns  the function object that compares the values. It is the same as
     key_comp.

Parameters
	(none)

Return value
	The value comparison function object.

Complexity
	Constant.

Example
     // Run this code

      #include <iostream>
      #include <flat_set>
      #include <utility>

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

      int main()
      {
	  std::flat_set<int, ModCmp> cont{1, 2, 3, 4, 5};

	  // Same behaviour as key_comp()
	  auto comp_func = cont.value_comp();

	  for (const int val{100}; const int key : cont)
	  {
	      const bool before = comp_func(key, val);
	      const bool after = comp_func(val, key);

	      std::cout << "Key (" << key << ") ";
	      if (!before && !after)
		  std::cout << "equivalent to key (" << val << ")\n";
	      else if (before)
		  std::cout << "goes before key (" << val << ")\n";
	      else if (after)
		  std::cout << "goes after key (" << val << ")\n";
	      else
		  std::unreachable();
	  }
      }

Output:
      Key (1) goes before key (100)
      Key (2) goes before key (100)
      Key (3) equivalent to key (100)
      Key (4) goes after key (100)
      Key (5) goes after key (100)

See also
	key_comp returns the function that compares keys
		 (public member function)

http://cppreference.com 	   2024.06.10	    std::flat_set::value_comp(3)
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