Question

我目前正在玩boost::date_time。在这样做的同时，我遇到了days_until_weekday（documentation link）函数，这对我来说非常有用。不幸的是，我从以下代码段中得到了编译时错误

date f(date d){
    return next_weekday(d,  boost::date_time::weekdays::Friday);
}

读

> In file included from
> /usr/include/boost/date_time/gregorian/gregorian_types.hpp:25:0,
>                  from /usr/include/boost/date_time/posix_time/posix_time_config.hpp:18,
>                  from /usr/include/boost/date_time/posix_time/posix_time_system.hpp:13,
>                  from /usr/include/boost/date_time/posix_time/ptime.hpp:12,
>                  from /usr/include/boost/date_time/posix_time/posix_time.hpp:15,
>                  from prog.cpp:3: /usr/include/boost/date_time/date_generators.hpp: In instantiation of
> 'typename date_type::duration_type
> boost::date_time::days_until_weekday(const date_type&, const
> weekday_type&) [with date_type = boost::gregorian::date; weekday_type
> = boost::date_time::weekdays; typename date_type::duration_type = boost::gregorian::date_duration]':
> /usr/include/boost/date_time/date_generators.hpp:488:34:   required
> from 'date_type boost::date_time::next_weekday(const date_type&, const
> weekday_type&) [with date_type = boost::gregorian::date; weekday_type
> = boost::date_time::weekdays]' prog.cpp:11:67:   required from here /usr/include/boost/date_time/date_generators.hpp:452:37: error:
> request for member 'as_number' in 'wd', which is of non-class type
> 'const boost::date_time::weekdays'
>      duration_type dd(wd.as_number() - d.day_of_week().as_number());

转到here粘贴我的代码。

由于导致错误的片段很短，我真的没有想法解决这个问题。

顺便说一句，我使用clang 3.7.0来提升1.60.0。

Answer 1

您需要将date_time枚举转换为与传递给函数的weekday_type所期望的接口相匹配的对象。使用greg_weekday函数为您执行此操作，例如：

    return next_weekday(d, boost::gregorian::greg_weekday(boost::date_time::Friday));

在VS2015下为我编译并提升1.53。

此功能文档的链接： greg_weekday

boost :: date_time :: days_until_weekday

1 个答案: