key_compare key_comp() const; |
Returns the function object that compares the keys, which is a copy of this container's constructor argument comp. It is the same as value_comp.
(none).
The key comparison function object.
Constant.
#include <cassert>
#include <iostream>
#include <set>
// 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::set<int, ModCmp> cont{1, 2, 3, 4, 5};
auto comp_func = cont.key_comp();
for (int key : cont) {
bool before = comp_func(key, 100);
bool after = comp_func(100, key);
if (!before && !after)
std::cout << key << " equivalent to key 100\n";
else if (before)
std::cout << key << " goes before key 100\n";
else if (after)
std::cout << key << " goes after key 100\n";
else
assert(0); // Cannot happen
}
}Output:
1 goes before key 100 2 goes before key 100 3 equivalent to key 100 4 goes after key 100 5 goes after key 100
| returns the function that compares keys in objects of type value_type (public member function) |
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