std::ratio_less_equal

 

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编译时有理数算术
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integer_sequence (C++14)

 

编译时有理数算术

ratio (C++11)

算术

ratio_add (C++11)

ratio_subtract (C++11)

ratio_multiply (C++11)

ratio_divide (C++11)

比较

ratio_equal (C++11)

ratio_not_equal (C++11)

ratio_less (C++11)

ratio_less_equal (C++11)

ratio_greater (C++11)

ratio_greater_equal (C++11)

 

定义于头文件 <ratio>
template< class R1, class R2 > struct ratio_less_equal : std::integral_constant<bool, /* 见下方 */> { };		(自 C++11 起)

如果 ratio R1 小于或等于 ratio R2，则提供成员常量 value 等于 true。否则，value 为 false。

辅助变量模板

template< class R1, class R2 > constexpr bool ratio_less_equal_v = ratio_less_equal<R1, R2>::value;		(自 C++17 起)

继承自 std::integral_constant

成员常量

value [静态]

如果 R1::num * R2::den <= R2::num * R1::den，或避免溢出的等效表达式为真，则为 true，否则为 false (公共静态成员常量)

成员函数

operator bool	将对象转换为 bool，返回 value (公共成员函数)
operator() (C++14)	返回 value (公共成员函数)

成员类型

类型	定义
value_type	bool
type	std::integral_constant<bool, value>

示例

运行此代码

#include <iostream>
#include <ratio>
 
int main()
{
    static_assert(std::ratio_less_equal<std::ratio<1, 2>, std::ratio<3, 4>>::value,
                  "1/2 <= 3/4");
 
    if (std::ratio_less_equal<std::ratio<10,11>, std::ratio<11,12>>::value)
        std::cout << "10/11 <= 11/12" "\n";
 
    static_assert(std::ratio_less_equal_v<std::ratio<10, 11>, std::ratio<11, 12>>);
 
    if constexpr (std::ratio_less_equal_v<std::ratio<10, 11>, std::ratio<11, 12>>)
        std::cout << "11/12 <= 12/13" "\n";
}

输出

10/11 <= 11/12
11/12 <= 12/13

参见

ratio_equal (C++11)	在编译时比较两个 ratio 对象是否相等 (类模板)
ratio_not_equal (C++11)	在编译时比较两个 ratio 对象是否不等 (类模板)