blocks|key|4005490|text|请尝试以下操作|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4005491|var+col+=+GetTheCollection();
var+subset+=+col.Skip(250).Take(90);|code-block|syntax|javascript|4005492|或者更一般地说|4005493|public+static+IEnumerable<T>+GetRange(this+IEnumerable<T>+source,+int+start,+int+end)+{
++//+Error+checking+removed
++return+source.Skip(start).Take(end+-+start);
}|4005494|编辑+2.0解决方案|offset|length|style|BOLD|4005495|public+static+IEnumerable<T>+GetRange<T>(IEnumerable<T>+source,+int+start,+int+end+)+{
++using+(+var+e+=+source.GetEnumerator()+){+
++++var+i+=+0;
++++while+(+i+<+start+&&+e.MoveNext()+)+{+i%2B%2B;+}
++++while+(+i+<+end+&&+e.MoveNext()+)+{+
++++++yield+return+e.Current;
++++++i%2B%2B;
++++}
++}++++++
}

IEnumerable<Foo>+col+=+GetTheCollection();
IEnumerable<Foo>+range+=+GetRange(col,+250,+340);|4005496|entityMap^0|0|0|0|0|0|2|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|Y|8|@$M|Z|N|10|O|P]]|9|@]|A|$]]|$1|Q|3|R|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

Try the following

<pre><code>var col = GetTheCollection();
var subset = col.Skip(250).Take(90);
</code></pre>

Or more generally 

<pre><code>public static IEnumerable&lt;T&gt; GetRange(this IEnumerable&lt;T&gt; source, int start, int end) {
 // Error checking removed
 return source.Skip(start).Take(end - start);
}
</code></pre>

EDIT 2.0 Solution

<pre><code>public static IEnumerable&lt;T&gt; GetRange&lt;T&gt;(IEnumerable&lt;T&gt; source, int start, int end ) {
 using ( var e = source.GetEnumerator() ){ 
 var i = 0;
 while ( i &lt; start &amp;&amp; e.MoveNext() ) { i++; }
 while ( i &lt; end &amp;&amp; e.MoveNext() ) { 
 yield return e.Current;
 i++;
 }
 } 
}

IEnumerable&lt;Foo&gt; col = GetTheCollection();
IEnumerable&lt;Foo&gt; range = GetRange(col, 250, 340);
</code></pre>

blocks|key|4005531|text|您也许可以使用Linq来做一些事情。我这样做的方式是将对象放入一个数组中，然后我可以根据数组id选择要处理的项。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4005532|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You might be able to do something with Linq. The way I would do this is to put the objects into an array, then I can choose which items I want to process based on the array id.

blocks|key|1255880|text|如果您发现需要对列表和集合进行大量的切分和切分，那么学习the+C5+Generic+Collection+Library可能是值得的。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1255881|entityMap|0|LINK|mutability|MUTABLE|url|http://www.itu.dk/research/c5/^0|S|X|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

If you find that you need to do a fair amount of slicing and dicing of lists and collections, it might be worth climbing the learning curve into <a href="http://www.itu.dk/research/c5/" rel="nofollow noreferrer">the C5 Generic Collection Library</a>.

blocks|key|4851044|text|我喜欢保持简单(如果您不一定需要枚举器)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4851045|for+(int+i+=+249;+i+<+Math.Min(340,+list.Count);+i%2B%2B)
{
++++//+do+something+with+list[i]
}|code-block|syntax|javascript|4851046|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I like to keep it simple (if you don't necessarily need the enumerator):

<pre><code>for (int i = 249; i &lt; Math.Min(340, list.Count); i++)
{
 // do something with list[i]
}
</code></pre>

blocks|key|787031|text|将Jared的原始代码改编为.Net+2.0：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|787032|IEnumerable<T>+GetRange(IEnumerable<T>+source,+int+start,+int+end)
{
++++int+i+=+0;
++++foreach+(T+item+in+source)
++++{
++++++++i%2B%2B;
++++++++if+(i>end)+yield+break;
++++++++if+(i>start)+yield+return+item;
++++}
}|code-block|syntax|javascript|787033|并使用它：|787034|+foreach+(T+item+in+GetRange(MyCollection,+250,+340))
+{
+++++//+do+something
+}|787035|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Adapting Jared's original code for .Net 2.0:

<pre><code>IEnumerable&lt;T&gt; GetRange(IEnumerable&lt;T&gt; source, int start, int end)
{
 int i = 0;
 foreach (T item in source)
 {
 i++;
 if (i&gt;end) yield break;
 if (i&gt;start) yield return item;
 }
}
</code></pre>

And to use it:

<pre><code> foreach (T item in GetRange(MyCollection, 250, 340))
 {
 // do something
 }
</code></pre>

blocks|key|4005680|text|再次调整Jarad的代码，这个扩展方法将得到一个由项目定义的子集，而不是索引。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4005681|++++//!+Get+subset+of+collection+between+\a+start+and+\a+end,+inclusive
++++//!+Usage
++++//!+\code
++++//!+using+ExtensionMethods;
++++//!+...
++++//!+var+subset+=+MyList.GetRange(firstItem,+secondItem);
++++//!+\endcode
class+ExtensionMethods
{
++++public+static+IEnumerable<T>+GetRange<T>(this+IEnumerable<T>+source,+T+start,+T+end)
++++{
#if+DEBUG
++++++++if+(source.ToList().IndexOf(start)+>+source.ToList().IndexOf(end))
++++++++++++throw+new+ArgumentException("Start+must+be+earlier+in+the+enumerable+than+end,+or+both+must+be+the+same");
#endif
++++++++yield+return+start;

++++++++if+(start.Equals(end))
++++++++++++yield+break;++++++++++++++++++++++++++++++++++++++++++++++++++++//start+==+end,+so+we+are+finished+here

++++++++using+(var+e+=+source.GetEnumerator())
++++++++{+
++++++++++++while+(e.MoveNext()+&&+!e.Current.Equals(start));+++++++++++++++//skip+until+start++++++++++++++++
++++++++++++while+(!e.Current.Equals(end)+&&+e.MoveNext())++++++++++++++++++//return+items+between+start+and+end
++++++++++++++++yield+return+e.Current;
++++++++}
++++}
}|code-block|syntax|javascript|4005682|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Adapting Jarad's code once again, this extention method will get you a subset that is defined by item, not index.

<pre><code> //! Get subset of collection between \a start and \a end, inclusive
 //! Usage
 //! \code
 //! using ExtensionMethods;
 //! ...
 //! var subset = MyList.GetRange(firstItem, secondItem);
 //! \endcode
class ExtensionMethods
{
 public static IEnumerable&lt;T&gt; GetRange&lt;T&gt;(this IEnumerable&lt;T&gt; source, T start, T end)
 {
#if DEBUG
 if (source.ToList().IndexOf(start) &gt; source.ToList().IndexOf(end))
 throw new ArgumentException("Start must be earlier in the enumerable than end, or both must be the same");
#endif
 yield return start;

 if (start.Equals(end))
 yield break; //start == end, so we are finished here

 using (var e = source.GetEnumerator())
 { 
 while (e.MoveNext() &amp;&amp; !e.Current.Equals(start)); //skip until start 
 while (!e.Current.Equals(end) &amp;&amp; e.MoveNext()) //return items between start and end
 yield return e.Current;
 }
 }
}
</code></pre>

Is there a good way to enumerate through only a subset of a Collection in C#? That is, I have a collection of a large number of objects (say, 1000), but I'd like to enumerate through only elements 250 - 340. Is there a good way to get an Enumerator for a subset of the collection, without using another Collection?

Edit: should have mentioned that this is using .NET Framework 2.0.

Enumerate through a subset of a Collection in C#?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

有没有一种很好的方法来在C#中只枚举集合的一个子集？也就是说，我有一个包含大量对象(比如1000个)的集合，但我只想枚举250 - 340个元素。有没有一种好的方法来获得集合的子集的枚举数，而不使用另一个集合？编辑:应该提到它使用的是.NET Framework2.0。

问在C#中枚举集合的子集吗？
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问在C#中枚举集合的子集吗？EN