std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::key_comp
From cppreference.com
| key_compare key_comp() const; |
(since C++23) | |
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 <iostream> #include <flat_map> #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_map<int, char, ModCmp> cont; cont = {{1, 'a'}, {2, 'b'}, {3, 'c'}, {4, 'd'}, {5, 'e'}}; auto comp_func = cont.key_comp(); for (const auto it : cont) { const bool before = comp_func(it.first, 100); const bool after = comp_func(100, it.first); std::cout << "Key (" << 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 std::unreachable(); } }
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
returns the function that compares keys in objects of type value_type (public member function) |