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位标记-我缺少什么?

bit-manipulation c#

balexandre · 技术社区 · 14 年前

一个简单的代码:

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);
}

帮手:

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); }

今日产量(周六)

now.DayOfWeek: Saturday
True
True
True
True
True
True

但是输出应该是这样的:

now.DayOfWeek: Saturday
False
False
False
True
True
True

我这里缺什么?

5 回复 | 直到 13 年前

Yakimych 14 年前

一周中的几天不是小旗。 http://msdn.microsoft.com/en-us/library/system.datetime.dayofweek.aspx

中常量的值 DayOfWeek枚举的范围为星期几。星期日到星期几。星期六。如果铸造成整数,其值范围为零 (表示dayofweek.sunday)至六(表示星期几,星期六)。

Ales Potocnik Hahonina 13 年前

我知道这是一篇旧的文章,但以防万一——做标记枚举的一个简洁语法是

[Flags]
public enum DaysOfWeek
{
    None = 1 << 0,
    Monday = 1 << 1,
    Tuesday = 1 << 2,
    Wednesday = 1 << 3,
    Thursday = 1 << 4,
    Friday = 1 << 5,
    Saturday = 1 << 6,
    Sunday = 1 << 7
}

您将需要“无”来指示未选择任何内容。这样的枚举允许您指示多天,例如:

var selectedDays = DaysOfWeek.Tuesday | DaysOfWeek.Friday;

希望不需要评论。为了“解码”该值:

public bool IsDayOfWeekSelected(DaysOfWeek which, DaysOfWeek selection)
{
    return selection & which == which;
}

然后我们可以打电话给:

var isTuesday = IsDayOfWeekSelected(DaysOfWeek.Tuesday, selectedDays); // => true
var isWednesday = IsDayOfWeekSelected(DaysOfWeek.Wednesday, selectedDays); // => false
var isFriday = IsDayOfWeekSelected(DaysOfWeek.Friday, selectedDays); // => true

希望这能帮助别人。

Ray 14 年前

如果需要像标记一样使用DayOfWeek枚举,则可以创建自己的DayOfWeek枚举:

[Flags]
public enum MyDayOfWeek { Sunday = 1, Monday = 2, Tuesday = 4, ... , Saturday = 64 };

Albin Sunnanbo 14 年前

DayOfWeek有序列号。

使用A List<DayOfWeek> .

转到定义显示:

// Summary:
//     Specifies the day of the week.
[Serializable]
[ComVisible(true)]
public enum DayOfWeek
{
    // Summary:
    //     Indicates Sunday.
    Sunday = 0,
    //
    // Summary:
    //     Indicates Monday.
    Monday = 1,
    //
    // Summary:
    //     Indicates Tuesday.
    Tuesday = 2,
    //
    // Summary:
    //     Indicates Wednesday.
    Wednesday = 3,
    //
    // Summary:
    //     Indicates Thursday.
    Thursday = 4,
    //
    // Summary:
    //     Indicates Friday.
    Friday = 5,
    //
    // Summary:
    //     Indicates Saturday.
    Saturday = 6,
}

dan04 14 年前

这个 DayOfWeek 枚举的目的是表示一周中的一天,而不是一组天。

使用时不会出现编译器错误 & 因为枚举是整数,但运算符不执行您期望的操作(除非您碰巧只在周一、周二或周四安排事件)。

如果您想要一个位标志,那么声明一个位标志类型,就像Ray建议的那样。