std::ratio_less

 

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編譯時有理數算術
編譯時整數序列
integer_sequence (C++14)

 

編譯時有理數算術

ratio (C++11)

算術

ratio_add (C++11)

ratio_subtract (C++11)

ratio_multiply (C++11)

ratio_divide (C++11)

比較

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)

 

定義於標頭檔案 <ratio>
template< class R1, class R2 > struct ratio_less : std::integral_constant<bool, /* see below */> { };		(C++11 起)

如果比例 R1 小於比例 R2，則提供成員常量 value 等於 true。否則，value 為 false。

輔助變數模板

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

繼承自 std::integral_constant

成員常量

value [靜態]

如果 R1::num * R2::den < R2::num * R1::den，或等效的避免溢位的表示式，則為 true，否則為 false (public static 成員常量)

成員函式

operator bool	將物件轉換為 bool，返回 value (公開成員函式)
operator() (C++14)	返回 value (公開成員函式)

成員型別

型別	定義
value_type	bool
型別	std::integral_constant<bool, value>

示例

執行此程式碼

#include <iostream>
#include <ratio>
 
int main()
{
    using x = std::ratio<69, 90>;
    using y = std::ratio<70, 90>;
 
    if constexpr (std::ratio_less_v<x, y>)
        std::cout << x::num << '/' << x::den << " < "
                  << y::num << '/' << y::den << '\n';
}

輸出

23/30 < 7/9

另請參見

ratio_greater (C++11)

在編譯時比較兩個 ratio 物件是否“大於” (類模板)