multiplies 的定义

// STRUCT TEMPLATE multiplies
template<class _Ty = void>
	struct multiplies
	{	// functor for operator*
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty first_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty second_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty result_type;

	constexpr _Ty operator()(const _Ty& _Left, const _Ty& _Right) const
		{	// apply operator* to operands
		return (_Left * _Right);
		}
	};

使用示例

#include<iostream>
#include<algorithm>
using namespace std;
int main(int argc, char** argv){
    int x = multiplies<int>()(3,4);
    if(not_equal_to<int>()(x,10)){
        cout<<x<<endl;
    }
    return 0;
}

类似的使用

定义的位置：

less greater greater_equal less_equal not_equal_to
logical_and logical_or logical_not
minus plus divide modulus negate

template<class _Ty = void>
	struct plus
	{	// functor for operator+
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty first_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty second_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty result_type;

	constexpr _Ty operator()(const _Ty& _Left, const _Ty& _Right) const
		{	// apply operator+ to operands
		return (_Left + _Right);
		}
	};

		// STRUCT TEMPLATE minus
template<class _Ty = void>
	struct minus
	{	// functor for operator-
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty first_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty second_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty result_type;

	constexpr _Ty operator()(const _Ty& _Left, const _Ty& _Right) const
		{	// apply operator- to operands
		return (_Left - _Right);
		}
	};

		// STRUCT TEMPLATE multiplies
template<class _Ty = void>
	struct multiplies
	{	// functor for operator*
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty first_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty second_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty result_type;

	constexpr _Ty operator()(const _Ty& _Left, const _Ty& _Right) const
		{	// apply operator* to operands
		return (_Left * _Right);
		}
	};

		// STRUCT TEMPLATE equal_to
template<class _Ty = void>
	struct equal_to
	{	// functor for operator==
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty first_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty second_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef bool result_type;

	constexpr bool operator()(const _Ty& _Left, const _Ty& _Right) const
		{	// apply operator== to operands
		return (_Left == _Right);
		}
	};

		// STRUCT TEMPLATE not_equal_to
template<class _Ty = void>
	struct not_equal_to
	{	// functor for operator!=
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty first_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty second_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef bool result_type;

	constexpr bool operator()(const _Ty& _Left, const _Ty& _Right) const
		{	// apply operator!= to operands
		return (_Left != _Right);
		}
	};

		// STRUCT TEMPLATE greater
template<class _Ty = void>
	struct greater
	{	// functor for operator>
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty first_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty second_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef bool result_type;

	constexpr bool operator()(const _Ty& _Left, const _Ty& _Right) const
		{	// apply operator> to operands
		return (_Left > _Right);
		}
	};

		// STRUCT TEMPLATE less
template<class _Ty = void>
	struct less
	{	// functor for operator<
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty first_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty second_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef bool result_type;

	constexpr bool operator()(const _Ty& _Left, const _Ty& _Right) const
		{	// apply operator< to operands
		return (_Left < _Right);
		}
	};

		// STRUCT TEMPLATE greater_equal
template<class _Ty = void>
	struct greater_equal
	{	// functor for operator>=
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty first_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty second_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef bool result_type;

	constexpr bool operator()(const _Ty& _Left, const _Ty& _Right) const
		{	// apply operator>= to operands
		return (_Left >= _Right);
		}
	};

		// STRUCT TEMPLATE less_equal
template<class _Ty = void>
	struct less_equal
	{	// functor for operator<=
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty first_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef _Ty second_argument_type;
	_CXX17_DEPRECATE_ADAPTOR_TYPEDEFS typedef bool result_type;

	constexpr bool operator()(const _Ty& _Left, const _Ty& _Right) const
		{	// apply operator<= to operands
		return (_Left <= _Right);
		}
	};

标签：CXX17,const,Ty,ADAPTOR,multiplies,operator,DEPRECATE
来源： https://www.cnblogs.com/cyssmile/p/12790854.html