std::ratio_greater_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)

 

在标头 <ratio> 定义
template< class R1, class R2 > struct ratio_greater_equal : std::integral_constant<bool, /* see below */> { };		(C++11 起)

若比例 R1 大于或等于比例 R2 ，则提供等于 true 的成员常量 value 。否则 value 等于 false 。

辅助变量模板

template< class R1, class R2 > inline constexpr bool ratio_greater_equal_v = ratio_greater_equal<R1, R2>::value;		(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 或避免溢出的等价表达式成立，那么是 true，否则是 false (公开静态成员常量)

成员函数

operator bool	将对象转换到 bool，返回 value (公开成员函数)
operator() (C++14)	返回 value (公开成员函数)

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 <ratio>
#include <iostream>
 
auto main() -> int
{
    static_assert(std::ratio_greater_equal<
        std::ratio<2, 3>, 
        std::ratio<2, 3>>::value, "2/3 >= 2/3");
 
    if (std::ratio_greater_equal<
        std::ratio<2,1>, std::ratio<1, 2>>::value) {
        std::cout << "2/1 >= 1/2" "\n";
    }
 
    if (std::ratio_greater_equal<
        std::ratio<1,2>, std::ratio<1, 2>>::value) {
        std::cout << "1/2 >= 1/2" "\n";
    }
 
    // C++17 起
    static_assert(std::ratio_greater_equal_v<
        std::ratio<999'999, 1'000'000>, 
        std::ratio<999'998, 999'999>> );
 
    if constexpr (std::ratio_greater_equal_v<
        std::ratio<999'999, 1'000'000>, 
        std::ratio<999'998, 999'999>>) {
        std::cout << "999'999/1'000'000 >= 999'998/999'999" "\n";
    }
    if constexpr (std::ratio_greater_equal_v<
        std::ratio<999'999, 1'000'000>, 
        std::ratio<999'999, 1'000'000>>) {
        std::cout << "999'999/1'000'000 >= 999'999/1'000'000" "\n";
    }
}

输出：

2/1 >= 1/2
1/2 >= 1/2
999'999/1'000'000 >= 999'998/999'999
999'999/1'000'000 >= 999'999/1'000'000