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std::greater

Defined in header `<functional>`
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.

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)

std::ranges::equal_to, std::ranges::not_equal_to, std::ranges::less, std::ranges::greater, std::ranges::less_equal, std::ranges::greater_equal, and std::compare_three_way

(since C++20)

Specializations

greater<void>

(C++14)

function object implementing x > y deducing argument 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
}

less	function object implementing `x < y` (class template)
ranges::greater (C++20)	function object implementing `x > y` (class)