std::set<Key,Compare,Allocator>::value_comp - cppreference.com (original) (raw)

| value_compare value_comp() const; | | (constexpr since C++26) | | ----------------------------------- | | ----------------------- |

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

[edit] Return value

The value comparison function object.

[edit] Complexity

Constant.

[edit] Example

#include #include #include   // Example module 97 key compare function struct ModCmp { bool operator()(int lhs, int rhs) const { return (lhs % 97) < (rhs % 97); } };   int main() { std::set<int, ModCmp> cont{1, 2, 3, 4, 5};   // Same behavior 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)

[edit] See also

| | returns the function that compares keys (public member function) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |