C ++ 17更新

Question

如果我转换为较粗略的时间单位（比如class Employee::ProfilesController < EmployeeController before_action :set_company_employee ... def set_company_employee if params[:employee_id] # Line that throws error below : @employee = (Company::Employee).find(params[:employee_id]) else # Many employee profiles, bad request flashy_now(:error, :select_employee_profiles) redirect_back end @company = @employee.company end class Company::Employee < Professional include Invitable belongs_to :company belongs_to :entity delegate :name, to: :company, prefix: true delegate :name, to: :entity, prefix: true, allow_nil: true end class Professional include Mongoid::Document include Mongoid::Timestamps include SimpleEnum::Mongoid include Likeable include UserProfile ... belongs_to :user ...到std::chrono::minutes），std::chrono::hours将如何转换？例如，如果转换为duration_cast，std::chrono::minutes(91)会变成什么值？ 2小时，1小时？

Answer 1

duration_cast总是向零舍入。即正值向下舍入，负值向上舍入。

有关其他舍入选项，请参阅：

http://howardhinnant.github.io/duration_io/chrono_util.html

floor，ceil和round目前正在草案C ++ 1z（希望是C ++ 17）草案工作文件中。在此期间，您可以随意使用chrono_util.html处的代码，如果您有任何问题，请与我们联系。

C ++ 17更新

std::chrono::floor<std::chrono::seconds>(1400ms)  ==  1s
std::chrono::floor<std::chrono::seconds>(1500ms)  ==  1s
std::chrono::floor<std::chrono::seconds>(1600ms)  ==  1s
std::chrono::floor<std::chrono::seconds>(-1400ms) == -2s
std::chrono::floor<std::chrono::seconds>(-1500ms) == -2s
std::chrono::floor<std::chrono::seconds>(-1600ms) == -2s

duration_cast怎么回合

1 个答案:

C ++ 17更新