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std:: ratio_greater

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

如果比例 R1 大于比例 R2 ，则提供值为 true 的成员常量 value 。否则， value 为 false 。

目录

Helper variable template

template < class R1, class R2 >
constexpr bool ratio_greater_v = ratio_greater < R1, R2 > :: value ;
(C++17 起)

继承自 std:: integral_constant

成员常量

value
[static]
若 R1 :: num * R2 :: den > R2 :: num * R1 :: den 或等效的避免溢出的表达式成立，则为 true ，否则为 false
（公开静态成员常量）

成员函数

operator bool
转换对象为 bool 类型，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 <iostream>
#include <ratio>
int main()
{
    static_assert(std::ratio_greater<std::ratio<3, 4>, std::ratio<1, 2>>::value,
                  "3/4 > 1/2");
    if (std::ratio_greater<std::ratio<11, 12>, std::ratio<10, 11>>::value)
        std::cout << "11/12 > 10/11" "\n";
    // 自 C++17 起
    static_assert(std::ratio_greater_v<std::ratio<12, 13>, std::ratio<11, 12>>);
    if constexpr (std::ratio_greater_v<std::ratio<12, 13>, std::ratio<11, 12>>)
        std::cout << "12/13 > 11/12" "\n";
}

输出： 

11/12 > 10/11
12/13 > 11/12

参见

(C++11)
在编译时比较两个 ratio 对象是否满足 大于等于 关系
(类模板)