std::set<Key,Compare,Allocator>::key_comp
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key_compare key_comp() const; |
(constexpr since C++26) | |
Returns the function object that compares the keys, which is a copy of the key comparison object used by *this.It is the same as value_comp().
Contents |
[edit] Return value
The key comparison function object.
[edit] Complexity
Constant.
[edit] Example
Run this code
#include <iostream> #include <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::set<int, ModCmp> cont{1, 2, 3, 4, 5}; auto comp_func = cont.key_comp(); for (const int key : cont) { const bool before = comp_func(key, 100); const bool after = comp_func(100, key); std::cout << '(' << key << ") "; 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:
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 in objects of type value_type (public member function) [edit] |
