std::map<Key,T,Compare,Allocator>::key_comp
From cppreference.com
key_compare key_comp() const; |
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Returns the function object that compares the keys, which is a copy of this container's constructor argument comp
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Contents |
[edit] Parameters
(none)
[edit] Return value
The key comparison function object.
[edit] Complexity
Constant.
[edit] 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::map<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
[edit] See also
returns the function that compares keys in objects of type value_type (public member function) |