std::less<void>

Since C++14

Header: <functional>

std::less is a specialization of std::less with parameter and return type deduced.

# Declarations

template<>
class less<void>;

(since C++14)

# Parameters

lhs, rhs: values to compare

# Return value

std::forward(lhs) < std::forward(rhs).

# Example

#include <algorithm>
#include <functional>
 
constexpr bool strictly_negative(int lhs)
{
    return std::less<>()(lhs, 0);
}
 
int main()
{
    constexpr signed low = 010;
    constexpr unsigned high = 10;
    std::less<> less{};
    static_assert(less(low, high));
 
    constexpr static auto arr = {0, -1, -2, -3, -4, -5};
    static_assert(!std::all_of(arr.begin(), arr.end(), strictly_negative));
    static_assert(std::all_of(arr.begin() + 1, arr.end(), strictly_negative));
}

# Defect reports

DR	Applied to	Behavior as published	Correct behavior
LWG 2562	C++98	the pointer total order might be inconsistent	guaranteed to be consistent