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std::less_equal

Defined in header `<functional>`
template< class T > struct less_equal;		(until C++14)
template< class T = void > struct less_equal;		(since C++14)

Function object for performing comparisons. Unless specialized, invokes operator<= on type T.

Specializations

A specialization of std::less_equal for any pointer type yields a total order, even if the built-in operator<= does not.

If the function call operator of the specialization std::less_equal<void> calls a built-in operator comparing pointers, it yields a total order, even if the built-in operator<= does not. (since C++14).

The standard library provides a specialization of std::less_equal when T is not specified, which leaves the parameter types and return type to be deduced.

less_equal<void>

function object implementing x <= y deducing argument and return types
(class template specialization)

(since C++14)

Member types

type	definition
`result_type`(deprecated in C++17)	`bool`
`first_argument_type`(deprecated in C++17)	`T`
`second_argument_type`(deprecated in C++17)	`T`

Member functions

operator()

checks if the first argument is less than or equal to the second
(public member function)

std::less_equal::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 if lhs is less than or equal to rhs.

Parameters

lhs, rhs

values to compare

Return value

true if lhs <= rhs, false otherwise.

Exceptions

(none).

Possible implementation

constexpr bool operator()(const T &lhs, const T &rhs) const 
{
    return lhs <= rhs;
}

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http://en.cppreference.com/w/cpp/utility/functional/less_equal