NAME¶

std::set::key_comp - std::set::key_comp

Synopsis¶

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.

Parameters¶

(none)

Return value¶

The key comparison function object.

Complexity¶

Constant.

Example¶

// Run this code

#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

See also¶

value_comp returns the function that compares keys in objects of type value_type
(public member function)