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<chrono> functions

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chrono literals duration_cast Function time_point_cast Function

chrono literals

(C++14) The <chrono> header defines 12 user-defined literals to facilitate using literals that represent hours, minutes, seconds, milliseconds, microseconds, and nanoseconds. Each user-defined literal has an integral and a floating-point overload. The literals are defined in the literals::chrono_literals inline namespace which is brought into scope automatically when std::chrono is in scope.

inline namespace literals {  
    inline namespace chrono_literals {  
 // return integral hours  
    constexpr chrono::hours operator"" h(unsigned long long Val);

 // return floating-point hours  
    constexpr chrono::duration<double, ratio<3600>> operator"" h(long double Val);

 // return integral minutes  
    constexpr chrono::minutes(operator"" min)(unsigned long long Val);

 // return floating-point minutes  
    constexpr chrono::duration<double, ratio<60>>(operator"" min)(long double Val);

 // return integral seconds  
    constexpr chrono::seconds operator"" s(unsigned long long Val);

 // return floating-point seconds  
    constexpr chrono::duration<double> operator"" s(long double Val);

 // return integral milliseconds  
    constexpr chrono::milliseconds operator"" ms(unsigned long long Val);

 // return floating-point milliseconds  
    constexpr chrono::duration<double, milli> operator"" ms(long double Val);

 // return integral microseconds      
    constexpr chrono::microseconds operator"" us(unsigned long long Val);

 // return floating-point microseconds  
    inline constexpr chrono::duration<double, micro> operator"" us(long double Val);

 // return integral nanoseconds  
    inline constexpr chrono::nanoseconds operator"" ns(unsigned long long Val);

 // return floating-point nanoseconds  
    constexpr chrono::duration<double, nano> operator"" ns(long double Val);

 }// inline namespace chrono_literals  
}// inline namespace literals

Remarks

Example

The following examples sow how to use the chrono literals.

constexpr auto day = 24h;  
constexpr auto week = 24h* 7;  
constexpr auto my_duration_unit = 108ms;

duration_cast Function

Casts a duration object to a specified type.

template <class To, class Rep, class Period>  
constexpr To duration_cast(const duration<Rep, Period>& Dur);

Return Value

A duration object of type To that represents the time interval Dur, which is truncated if it has to fit into the target type.

Remarks

If To is an instantiation of duration, this function does not participate in overload resolution.

time_point_cast Function

Casts a time_point object to a specified type.

template <class To, class Clock, class Duration>  
time_point<Clock, To>  
time_point_cast(
    const time_point<Clock, Duration>& Tp);

Return Value

A time_point object that has a duration of type To.

Remarks

Unless To is an instantiation of duration, this function does not participate in overload resolution.

See Also

<chrono>