Linq加入 - 有更好的方法吗？ [英] Linq join - is there a better way?

问题描述

我必须解析一个日期字符串。年，月和日都可以采用各种格式（年份为yy或yyyy）。



要获得一系列有效格式，我有每个日期 - 部分在一个单独的数组中。我使用Join（此Enumerable源）linq扩展将所有这些连接在一起。代码如下：

Hi,

I have to parse a date string. the year, month and day can all be in various formats (year in "yy" or "yyyy").

To get an array of valid formats, I have each date-part in a separate array. I join all of these together using the Join(this Enumerable source) linq extension. Code below:

private string[] years = { "yy", "yyy" };
private string[] months = { "M", "MM" };
private string[] days = { "d", "dd" };

string[] formats
{
    get
    {
        return years.Join(
                months,
                y => 1,
                m => 1,
                (y, m) => new {y, m}
            ).Join(
                days,
                n => 1,
                d => 1,
                (n, d) => string.Join("/", n.y, n.m, d)
            ).ToArray();
    }
}

我相信你能看到我不知道的一点喜欢。加入表1 = 1，bleh！



我更喜欢扩展语法到linq语法，所以我不会使用它，但它的受欢迎程度使谷歌搜索全部更难。



所以：我应该如何加入这些阵列？



谢谢^ _ ^

Andy

I'm sure you can see the bit I don't like. Joining tables on 1=1, bleh!

I prefer extension syntax to linq syntax, so I won't be using that, but it's popularity makes google searches all the more difficult.

So: How SHOULD I be joining these arrays?

Thanks ^_^
Andy

推荐答案

SelectMany [ ^ ]可能更合适：

SelectMany[^] would probably be a better fit:

return years
    .SelectMany(y => months, (y, m) => new { y, m })
    .SelectMany(ym => days, (ym, d) => ym.y + "/" + ym.m + "/" + d })
    .ToArray();

等效查询语法为：

The equivalent query syntax would be:

var query = from y in years
            from m in months
            from d in days
            select y + "/" + m + "/" + d;

return query.ToArray();

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