Question

a simple code:

protected void Page_Load(object sender, EventArgs e)
{
    DateTime now = DateTime.UtcNow;

    lit.Text += "<br/>now.DayOfWeek: " + now.DayOfWeek.ToString();

    // weekdays (Saturday is not included)
    DayOfWeek runningDays = DayOfWeek.Monday | DayOfWeek.Tuesday | DayOfWeek.Wednesday | DayOfWeek.Thursday | DayOfWeek.Friday;

    lit.Text += "<br/>" + runningDays.HasFlag(now.DayOfWeek);
    lit.Text += "<br/>" + runningDays.HasAny(now.DayOfWeek);
    lit.Text += "<br/>" + ((runningDays & now.DayOfWeek) != 0);

    // weekend (Saturday is in a weekend)
    runningDays = DayOfWeek.Saturday | DayOfWeek.Sunday;

    lit.Text += "<br/>" + runningDays.HasFlag(now.DayOfWeek);
    lit.Text += "<br/>" + runningDays.HasAny(now.DayOfWeek);
    lit.Text += "<br/>" + ((runningDays & now.DayOfWeek) != 0);
}

A helper:

public static bool HasExactly(this DayOfWeek x, DayOfWeek y) { return x == y; }
public static bool HasAny(this DayOfWeek x, DayOfWeek y) { return 0 != (x & y); }
public static bool HasAll(this DayOfWeek x, DayOfWeek y) { return y == (x & y); }

today’s output (Saturday)

now.DayOfWeek: Saturday
True
True
True
True
True
True 

But the output should be like:

now.DayOfWeek: Saturday
False
False
False
True
True
True 

What am I missing here?

Answer 1

Days of week are not bit flags. http://msdn.microsoft.com/en-us/library/system.datetime.dayofweek.aspx

The value of the constants in the
DayOfWeek enumeration ranges from
DayOfWeek.Sunday to
DayOfWeek.Saturday. If cast to an
integer, its value ranges from zero
(which indicates DayOfWeek.Sunday) to
six (which indicates
DayOfWeek.Saturday).