不确定它应该是什么类型

Question

我想提取当月的所有星期日,并拥有以下代码:

 private string GetDatesOfSundays(DateTime DatMonth)
 {
  string sReturn = "";
  int iDayOffset = DatMonth.Day - 1;
  DatMonth = DatMonth.AddDays(System.Convert.ToDouble(-DatMonth.Day + 1));
  DateTime DatMonth2 = DatMonth.AddMonths(1).AddDays(System.Convert.ToDouble(-1));
  while (DatMonth < DatMonth2)
  {
    if (DatMonth.DayOfWeek == System.DayOfWeek.Sunday)
    {
      if (sReturn.Length > 0) sReturn += ",";
      sReturn += DatMonth.ToShortDateString();
    }
    DatMonth = DatMonth.AddDays(1.0);
  }
  return sReturn;
}   

[HttpGet]
public ActionResult TradeUKKPISearchesData()
{
  string allSundaysInMonth = GetDatesOfSundays(System.DateTime.Now);  
  //var reportData = _reportingService.GetTradeUKKPISearches();
  //return View(reportData);
}

问题在于我的所有类型字符串for allSundaysInMonth,也是空的.sReturn是字符串类型,但我再次传递一个日期(我知道:))但是allSundaysInMonth应该是什么类型？sReturn确实有正确的日期...我需要在控制器视图的下拉列表中显示这些日期,以便用户可以选择他/她需要为其运行报告的任何星期日.

谢谢

Answer 1

怎么样

private IEnumerable<DateTime> GetDatesOfSundays(DateTime DatMonth)
{
    int iDayOffset = DatMonth.Day - 1;   
    DatMonth = DatMonth.AddDays(System.Convert.ToDouble(-DatMonth.Day + 1));
    DateTime DatMonth2 =
        DatMonth.AddMonths(1).AddDays(System.Convert.ToDouble(-1));
    while (DatMonth < DatMonth2)
    {
        if (DatMonth.DayOfWeek == System.DayOfWeek.Sunday)
        {
            yield return DatMonth;
        }

        DatMonth = DatMonth.AddDays(1.0);
    }
}

我很想把你的函数重写为这样的扩展

public static IEnumerable<Datetime> DaysOfMonth(
    this DateTime any,
    DayOfWeek day)
{
    // start at first of month
    var candidate = new DateTime(any.Year, any.Month, 1);

    var offset = (int)day - (int)candidate.DayOfWeek;

    if (offset < 0)
    {
        offset += 7
    }

    candidate = candidate.AddDays(offset);

    while (cadidate.Month == any.Month)
    {
        yield return candidate;
        candidate = candidate.AddDays(7.0)
    }
}

然后你可以像这样使用它

var allSundaysInMonth = DateTime.Now.DaysOfMonth(DayOfWeek.Sunday);

如果你想将IEnumerable<DateTime>a 转换成a,string你可以这样做,

var listOfDates = string.Join<DateTime>(", ", allSundaysInMonth);

使用这个 string.Join重载

如果你真的想要这样的日子DateTime[]你可以做到这一点(但没有必要)

DateTime[] allSundaysInMonth = GetDatesOfSundays(DateTime.Now).ToArray();

或者我的扩展示例

var allSundaysInMonth = DateTime.Now.DaysOfMonth(DayOfWeek.Sunday).ToArray();