Standard library header <ratio> (C++11)

 

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This header is part of the compile-time rational arithmetic library.

Classes
ratio (C++11)	represents exact rational fraction (class template)
Arithmetic
ratio_add (C++11)	adds two ratio objects at compile-time (alias template)
ratio_subtract (C++11)	subtracts two ratio objects at compile-time (alias template)
ratio_multiply (C++11)	multiplies two ratio objects at compile-time (alias template)
ratio_divide (C++11)	divides two ratio objects at compile-time (alias template)
Comparison
ratio_equal (C++11)	compares two ratio objects for equality at compile-time (class template)
ratio_not_equal (C++11)	compares two ratio objects for inequality at compile-time (class template)
ratio_less (C++11)	compares two ratio objects for less than at compile-time (class template)
ratio_less_equal (C++11)	compares two ratio objects for less than or equal to at compile-time (class template)
ratio_greater (C++11)	compares two ratio objects for greater than at compile-time (class template)
ratio_greater_equal (C++11)	compares two ratio objects for greater than or equal to at compile-time (class template)

Type Aliases
quecto (C++26)	std::ratio<1, 1000000000000000000000000000000>, if std::intmax_t can represent the denominator
ronto (C++26)	std::ratio<1, 1000000000000000000000000000>, if std::intmax_t can represent the denominator
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
ronna (C++26)	std::ratio<1000000000000000000000000000, 1>, if std::intmax_t can represent the numerator
quetta (C++26)	std::ratio<1000000000000000000000000000000, 1>, if std::intmax_t can represent the numerator

Synopsis

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, 1000000000000000000000000000000> quecto;
    typedef ratio<1,    1000000000000000000000000000> ronto;         
    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;
    typedef ratio<   1000000000000000000000000000, 1> ronna;
    typedef ratio<1000000000000000000000000000000, 1> quetta;
}