獲取給定開始日期，結束日期和星期幾的日期

Question

給定開始日期（DateTime），結束日期（DateTime）和DayOfWeek列表。 如何獲得所有匹配的日期：

范例：

StartDate : "06/17/2016" 
EndDate : "06/30/2016" 
DayOfWeek(s) : [0(Monday), 1(Tuesday), 4(Friday)]

想要的結果是：

Dates = ["06/17/2016", "06/20/2016", "06/21/2016", "06/24/2016", "06/27/2016", "06/28/2016"]

Answer 1

這將返回您在startDate和EndDate之間的所有日期列表，這些日期屬於dayOfWeek的給定枚舉：

var allDays = Enumerable.Range(0, (endDate - startDate).Days + 1).Select(d => startDate.AddDays(d));
var Dates = allDays.Where(dt => dayOfWeek.Contains(dt.DayOfWeek)).ToList();

Answer 2

還有另一種可能的解決方案，我認為這很容易理解和調試，即使它比其他可能的解決方案花費更多的行和更少的資源：

    var startDate = new DateTime(2016, 06, 17);
    var endDate = new DateTime(2016, 06, 30);

    DayOfWeek[] daysOfWeek = { DayOfWeek.Monday, DayOfWeek.Tuesday, DayOfWeek.Friday };

    List<DateTime> dates = new List<DateTime>();
    if (endDate >= startDate)
    {
        var tmp = startDate;
        tmp = tmp.AddDays(1); //I notice you didn't add 06/17/2016 that is friday, if you want to add it, just remove this line
        do
        {
            if (daysOfWeek.Contains(tmp.DayOfWeek))
                dates.Add(tmp);
            tmp = tmp.AddDays(1);
        }
        while (tmp <= endDate); //If you don't want to consider endDate just change this line into while (tmp < endDate); 
    }