ratio学习之ratio_add,ratio_subtract,ratio_multiply,ratio_divide的使用

ratio是比例类std::ratio代表一个比例，就是将给定的两个整数进行约分得到一个分数(分子及分母)，例如3/6,约分后就是1/2。它主要用于很小的单位，比如，毫秒，微秒，毫米，微米，纳米等。下面是ratio_add,ratio_subtract,ratio_multiply,ratio_divide的使用。

类
ratio	表示精确的有理分数 (类模板)
算术
ratio_add (C++11)	在编译时相加两个 ratio 对象 (别名模板)
ratio_subtract (C++11)	在编译时相减两个 ratio 对象 (别名模板)
ratio_multiply (C++11)	在编译时相乘两个 ratio 对象 (别名模板)
ratio_divide (C++11)	在编译时相除两个 ratio 对象 (别名模板)

#include <iostream>
#include <ratio>


using namespace std;

int main()
{
    ratio<2, 6> two_six;
    ratio<3, 6> three_six;

    cout << "two_six======" << two_six.num << "/" << two_six.den << endl;
    cout << "two_six======" << three_six.num << "/" << three_six.den << endl;

    cout << "Hello World!" << endl;
    return 0;
}

 ratio_add 两个ratio对象相加

#include <iostream>
#include <ratio>


using namespace std;

int main()
{
    ratio<2, 6> two_six;
    ratio<3, 6> three_six;

    cout << "two_six======" << two_six.num << "/" << two_six.den << endl;
    cout << "two_six======" << three_six.num << "/" << three_six.den << endl;

    ratio_add<decltype(two_six), decltype(three_six)> ratioAdd;
    cout << "ratio_add======" << ratioAdd.num << "/" << ratioAdd.den << endl;

    cout << "Hello World!" << endl;
    return 0;
}

ratio_subtract两个ratio对象相减

#include <iostream>
#include <ratio>


using namespace std;

int main()
{
    ratio<2, 6> two_six;
    ratio<3, 6> three_six;

    cout << "two_six======" << two_six.num << "/" << two_six.den << endl;
    cout << "two_six======" << three_six.num << "/" << three_six.den << endl;

    ratio_subtract<decltype(two_six), decltype(three_six)> ratioSubtract;
    cout << "ratio_subtract======" << ratioSubtract.num << "/" << ratioSubtract.den << endl;

    cout << "Hello World!" << endl;
    return 0;
}

 

ratio_multiply两个ratio对象相乘

#include <iostream>
#include <ratio>


using namespace std;

int main()
{
    ratio<2, 6> two_six;
    ratio<3, 6> three_six;

    cout << "two_six======" << two_six.num << "/" << two_six.den << endl;
    cout << "two_six======" << three_six.num << "/" << three_six.den << endl;

    ratio_multiply<decltype(two_six), decltype(three_six)> ratioMultiply;
    cout << "ratio_multiply======" << ratioMultiply.num << "/" << ratioMultiply.den << endl;

    cout << "Hello World!" << endl;
    return 0;
}

 ratio_divide两个ratio对象相除

#include <iostream>
#include <ratio>


using namespace std;

int main()
{
    ratio<2, 6> two_six;
    ratio<3, 6> three_six;

    cout << "two_six======" << two_six.num << "/" << two_six.den << endl;
    cout << "two_six======" << three_six.num << "/" << three_six.den << endl;

    ratio_divide<decltype(two_six), decltype(three_six)> ratioDivide;
    cout << "ratio_divide======" << ratioDivide.num << "/" << ratioDivide.den << endl;

    cout << "Hello World!" << endl;
    return 0;
}

 

参考：

标准库头文件 <ratio> - cppreference.com

C++11 std::chrono时间库_长乐村长的博客-CSDN博客_std::chrono