简单的 C# foreach 到 LINQ 问题

发布于 2024-11-08 06:41:33 字数 556 浏览 0 评论 0原文

目前有这个：

foreach (var series in Chart1.Series)
{
    series.Enabled = false;
}

我想用一个简单的一行表达式来表达这一点。我认为这会起作用：

Chart1.Series.Select( series => series.Enabled = false);

然而，这没有任何效果。大概是因为我只是误解了 Select 的工作原理，这很好。

我的下一个想法是做类似 Chart1.Series.ForEach(series => series.Enabled = false) 的事情，但是 Chart1.Series 没有实现 IEnumberable （..或者至少 ForEach 不是一个可接受的调用方法）。

我不想做 Chart1.Series = Chart1.Series.ToList().ForEach( series => series.Enabled = false);，但也许这是最简单的选择？

原文

Currently have this:

foreach (var series in Chart1.Series)
{
    series.Enabled = false;
}

I would like to express this in a simple, one line expression. I thought this would work:

Chart1.Series.Select( series => series.Enabled = false);

This doesn't have any effect, however. Presumably because I just misunderstood how Select was working, which is fine.

My next thought was to do something like Chart1.Series.ForEach( series => series.Enabled = false), but Chart1.Series does not implement IEnumberable (..or at least ForEach is not an acceptable method to call).

I'd rather not do Chart1.Series = Chart1.Series.ToList().ForEach( series => series.Enabled = false);, but maybe that is the simplest option?

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空袭的梦i 2024-11-15 06:41:33

对于您想要执行的操作，foreach 是首选。您正在迭代一系列元素并修改这些元素。这就是 foreach 的用途。

Linq 用于获取一个元素序列并根据某些标准/转换生成一个新序列。不是你所追求的。

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○愚か者の日 2024-11-15 06:41:33

简单，一行:)

foreach (var series in Chart1.Series) { series.Enabled = false; }

Simple and one line :)

foreach (var series in Chart1.Series) { series.Enabled = false; }

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好听的两个字的网名 2024-11-15 06:41:33

你的第一个 foreach 循环非常清晰并且有效，所以为什么需要用 LINQ 替换它，它不会更清晰或更快。

否则我想不会比你上面说的简单

Chart1.Series.ToList().ForEach( series => series.Enabled = false);

your first foreach loop is pretty clear and it works, so why need to replace it with LINQ, it wont be more clear or faster.

Otherwise I dont think it will be simpler than what you say above

Chart1.Series.ToList().ForEach( series => series.Enabled = false);

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向地狱狂奔 2024-11-15 06:41:33

至于 Select 不起作用的具体原因，请记住 Select 返回一个 IEnumerable，它是一个知道如何枚举的对象。换句话说，您引用了可以枚举的内容，但尚未被枚举。因此，如果您这样做：

var series = Chart1.Series.Select( s => s.Enabled = false);
foreach (var s in series) {}

您将获得您想要的效果，因为现在您正在枚举 Series 并因此调用 Select 委托。当然，这是相当不直观的，这就是为什么 Select 通常不以这种方式使用的原因（否则每次枚举时，都会产生副作用，并且枚举多次会再次应用副作用。）

As to the specific reason your Select didn't work, bear in mind that Select returns an IEnumerable<T>, which is an object that knows how to enumerate. In other words, you have a reference to something that can enumerate, but that hasn't yet been enumerated. So if you take this:

var series = Chart1.Series.Select( s => s.Enabled = false);
foreach (var s in series) {}

You'll get the effect you intended, because now you're enumerating the Series and therefore calling the Select delegate. This is rather non-intuitive, of course, which is why Select is typically not used in this way (otherwise every time you enumerate, you'll have side effects and enumerating more than once would apply the side effects again.)

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