Difference between revisions of "cpp/utility/functional/greater"
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===Return value=== | ===Return value=== | ||
| − | For {{tt|T}} which is not a pointer, {{c|true}} if {{c|1=lhs > rhs}}, {{c|false}} otherwise. | + | For {{tt|T}} which is not a pointer type, {{c|true}} if {{c|1=lhs > rhs}}, {{c|false}} otherwise. |
For {{tt|T}} which is a pointer type, {{c|true}} if {{tt|lhs}} succeeds {{tt|rhs}} in the implementation-defined strict total order, {{c|false}} otherwise. | For {{tt|T}} which is a pointer type, {{c|true}} if {{tt|lhs}} succeeds {{tt|rhs}} in the implementation-defined strict total order, {{c|false}} otherwise. | ||
Revision as of 23:23, 24 March 2021
| Defined in header <functional>
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template< class T > struct greater; |
(until C++14) | |
| template< class T = void > struct greater; |
(since C++14) | |
Function object for performing comparisons. Unless specialized, invokes operator> on type T.
Contents |
Implementation-defined strict total order over pointers
A specialization of std::greater for any pointer type yields the implementation-defined strict total order, even if the built-in > operator does not.
The implementation-defined strict total order is consistent with the partial order imposed by built-in comparison operators (<=>,(since C++20)<, >, <=, and >=), and consistent among following standard function objects:
- std::less, std::greater, std::less_equal, and std::greater_equal, when the template argument is a pointer type or void(since C++14)
| (since C++20) |
Specializations
| (C++14) |
function object implementing x > y deducing parameter and return types (class template specialization) |
Member types
| Type | Definition |
result_type (deprecated in C++17)(removed in C++20)
|
bool |
first_argument_type (deprecated in C++17)(removed in C++20)
|
T
|
second_argument_type (deprecated in C++17)(removed in C++20)
|
T
|
|
These member types are obtained via publicly inheriting std::binary_function<T, T, bool>. |
(until C++11) |
Member functions
| operator() |
checks whether the first argument is greater than the second (public member function) |
std::greater::operator()
bool operator()( const T& lhs, const T& rhs ) const; |
(until C++14) | |
| constexpr bool operator()( const T& lhs, const T& rhs ) const; |
(since C++14) | |
Checks whether lhs is greater than rhs.
Parameters
| lhs, rhs | - | values to compare |
Return value
For T which is not a pointer type, true if lhs > rhs, false otherwise.
For T which is a pointer type, true if lhs succeeds rhs in the implementation-defined strict total order, false otherwise.
Exceptions
May throw implementation-defined exceptions.
Possible implementation
constexpr bool operator()(const T &lhs, const T &rhs) const { return lhs > rhs; // assumes that the implementation uses a flat address space } |
See also
| function object implementing x < y (class template) |
