std::less<void>
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Defined in header
<functional>
template<>
class less<void>;
(since C++14)
class less<void>;
std::less <void> is a specialization of std::less with parameter and return type deduced.
Contents
[edit] Nested types
Nested type
Definition
is_transparent
unspecified
[edit] Member functions
operator()
(public member function)
std::less<void>::operator()
template< class T, class U >
constexpr auto operator()( T&& lhs, U&& rhs ) const
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.
[edit] Exceptions
May throw implementation-defined exceptions.
[edit] 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)); }
[edit] 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 |