Standard library header <ratio>
From cppreference.com
                    
                                        
                    
                    
                                                            
                    This header is part of the compile-time rational arithmetic library.
| 
 Classes | ||
| represents exact rational fraction (class template) | ||
| Arithmetic | ||
| (C++11) | adds two ratioobjects at compile-time(alias template) | |
| (C++11) | subtracts two ratioobjects at compile-time(alias template) | |
| (C++11) | multiplies two ratioobjects at compile-time(alias template) | |
| (C++11) | divides two ratioobjects at compile-time(alias template) | |
| Comparison | ||
| (C++11) | compares two ratioobjects for equality at compile-time(class template) | |
| (C++11) | compares two ratioobjects for inequality at compile-time(class template) | |
| (C++11) | compares two ratioobjects for less than at compile-time(class template) | |
| (C++11) | compares two ratioobjects for less than or equal to at compile-time(class template) | |
| (C++11) | compares two ratioobjects for greater than at compile-time(class template) | |
| (C++11) | compares two ratioobjects for greater than or equal to at compile-time(class template) | |
| Constants | ||
| yocto | std::ratio<1, 1000000000000000000000000>, if std::intmax_t can represent the denominator | |
| zepto | std::ratio<1, 1000000000000000000000>, if std::intmax_t can represent the denominator | |
| atto | std::ratio<1, 1000000000000000000> | |
| femto | std::ratio<1, 1000000000000000> | |
| pico | std::ratio<1, 1000000000000> | |
| nano | std::ratio<1, 1000000000> | |
| micro | std::ratio<1, 1000000> | |
| milli | std::ratio<1, 1000> | |
| centi | std::ratio<1, 100> | |
| deci | std::ratio<1, 10> | |
| deca | std::ratio<10, 1> | |
| hecto | std::ratio<100, 1> | |
| kilo | std::ratio<1000, 1> | |
| mega | std::ratio<1000000, 1> | |
| giga | std::ratio<1000000000, 1> | |
| tera | std::ratio<1000000000000, 1> | |
| peta | std::ratio<1000000000000000, 1> | |
| exa | std::ratio<1000000000000000000, 1> | |
| zetta | std::ratio<1000000000000000000000, 1>, if std::intmax_t can represent the numerator | |
| yotta | std::ratio<1000000000000000000000000, 1>, if std::intmax_t can represent the numerator | |
namespace std { //class template ratio template <intmax_t N, intmax_t D = 1> class ratio { public: typedef ratio<num, den> type; static constexpr intmax_t num; static constexpr intmax_t den; }; // ratio arithmetic template <class R1, class R2> using ratio_add = /*ratio*/; template <class R1, class R2> using ratio_subtract = /*ratio*/; template <class R1, class R2> using ratio_multiply = /*ratio*/; template <class R1, class R2> using ratio_divide = /*ratio*/; // ratio comparison template <class R1, class R2> struct ratio_equal; template <class R1, class R2> struct ratio_not_equal; template <class R1, class R2> struct ratio_less; template <class R1, class R2> struct ratio_less_equal; template <class R1, class R2> struct ratio_greater; template <class R1, class R2> struct ratio_greater_equal; // convenience SI typedefs typedef ratio<1, 1000000000000000000000000> yocto; typedef ratio<1, 1000000000000000000000> zepto; typedef ratio<1, 1000000000000000000> atto; typedef ratio<1, 1000000000000000> femto; typedef ratio<1, 1000000000000> pico; typedef ratio<1, 1000000000> nano; typedef ratio<1, 1000000> micro; typedef ratio<1, 1000> milli; typedef ratio<1, 100> centi; typedef ratio<1, 10> deci; typedef ratio< 10, 1> deca; typedef ratio< 100, 1> hecto; typedef ratio< 1000, 1> kilo; typedef ratio< 1000000, 1> mega; typedef ratio< 1000000000, 1> giga; typedef ratio< 1000000000000, 1> tera; typedef ratio< 1000000000000000, 1> peta; typedef ratio< 1000000000000000000, 1> exa; typedef ratio< 1000000000000000000000, 1> zetta; typedef ratio<1000000000000000000000000, 1> yotta; }