Observers

Method
Multimap
Returns the function that compares keys
key_compare key_comp() const noexcept;
Returns the function that compares keys in objects of type value_type
value_compare value_comp() const noexcept
SpatialMap
Returns the function that compares keys in a single dimension
dimension_compare dimension_comp() const noexcept;

Return value

A callable function that compares dimensions, keys, or values.

Complexity

\[ O(1) \]

Notes

These functions return copies of the container's constructor argument comp, or a wrappers around these copies.

Observers

These observers are useful in template functions that might receive spatial containers unknown to the function.

Most applications don't really need these observers. If you created the container, you already know the container compares its keys.

C++

auto fn = m.dimension_comp();
if (fn(2.,3.)) {
    std::cout << "2 is less than 3" << std::endl;
} else {
    std::cout << "2 is not less than 3" << std::endl;
}

Output

2 is less than 3