std::less<void>
From cppreference.com
| Defined in header <functional>
|
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template<> class less<void>; |
(since C++14) | |
std::less<void> is a specialization of std::less with parameter and return type deduced.
Nested types
| Nested type | Definition |
is_transparent
|
unspecified |
Member functions
tests if lhs compares less than rhs (public member function) |
std::less<void>::operator()
template< class T, class U > constexpr auto operator()( T&& lhs, U&& rhs ) const -> decltype(std::forward<T>(lhs) < std::forward<U>(rhs)); |
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Returns the result of std::forward<T>(lhs) < std::forward<U>(rhs).
Parameters
| lhs, rhs | - | values to compare |
Return value
std::forward<T>(lhs) < std::forward<U>(rhs).
If a built-in operator comparing pointers is called, the result is consistent with the implementation-defined strict total order over pointers.
Exceptions
May throw implementation-defined exceptions.
Example
Run this code
#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
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 2562 | C++98 | the pointer total order might be inconsistent | guaranteed to be consistent |