blocks|key|1830566|text|MyList.Sort有一个参数-负责比较项目的函数，因此可以根据它对列表进行排序。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1830567|接下来：委托(x，y)定义了函数本身，它接受两个类型为KeyValuePairString，Int32的参数。|1830568|括号{...}中的内容是实际的比较逻辑：|1830569|return+x.Value.CompareTo(y.Value);|code-block|syntax|javascript|1830570|它根据this+definition比较两个整数值。|1830571|因此，您的列表将根据这些整数的值按递增顺序进行排序。|1830572|1830573|使用C#+3.5，我会像这样重写它：|1830574|mylist.Sort((x,y)+=>+x.Value.CompareTo(y.Value));|1830575|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/system.icomparable.compareto.aspx^0|0|B|0|4|7|R|O|0|0|0|3|F|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|15|8|@$9|16|A|17|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|18|8|@$9|19|A|1A|B|C]|$9|1B|A|1C|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1D|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|1E|8|@]|D|@]|E|$M|N]]|$1|O|3|P|5|6|7|1F|8|@]|D|@$9|1G|A|1H|1|1I]]|E|$]]|$1|Q|3|R|5|6|7|1J|8|@]|D|@]|E|$]]|$1|S|3|-4|5|6|7|1K|8|@]|D|@]|E|$]]|$1|T|3|U|5|6|7|1L|8|@]|D|@]|E|$]]|$1|V|3|W|5|L|7|1M|8|@]|D|@]|E|$M|N]]|$1|X|3|-4|5|6|7|1N|8|@]|D|@]|E|$]]]|Y|$Z|$5|10|11|12|E|$13|14]]]]

MyList.Sort has one parameter - the function that is responsible for comparing items, so the list can be sorted accoding to it. 

Next: delegate(x,y) defines the function itself which accepts two parameters of type KeyValuePair[String, Int32]. 

The content in the brackets {...} is the actual comparisson logic:

<pre><code>return x.Value.CompareTo(y.Value);
</code></pre>

which compares 2 integer values according to <a href="http://msdn.microsoft.com/en-us/library/system.icomparable.compareto.aspx" rel="nofollow noreferrer">this definition</a>. 

Thus your list will be sorted based on the values of those integers in the accending order.

<hr>

With C# 3.5 I would rewrite it like this:

<pre><code>mylist.Sort((x,y) =&gt; x.Value.CompareTo(y.Value));
</code></pre>

blocks|key|528884|text|它是一个在列表上调用的排序函数，传递给它的对象是一个委托，Sort()调用该委托来实际执行两个元素之间的比较。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|528885|函数http://msdn.microsoft.com/en-us/library/0e743hdt.aspx上的MSDN页面|offset|length|528886|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/0e743hdt.aspx^0|0|2|1H|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|O|8|@]|9|@$D|P|E|Q|1|R]]|A|$]]|$1|F|3|-4|5|6|7|S|8|@]|9|@]|A|$]]]|G|$H|$5|I|J|K|A|$L|M]]]]

It is a sort function called on a list and the thing being passed into it is a delegate which is called by Sort() to actually do the comparison between two elements. 

MSDN page on the function
<a href="http://msdn.microsoft.com/en-us/library/0e743hdt.aspx" rel="nofollow noreferrer">http://msdn.microsoft.com/en-us/library/0e743hdt.aspx</a>

blocks|key|1931828|text|myList.Sort+//Sort+using+a+your+own+compare+function
++(
++++//+declare+the+compare+function,+returns+a+int,+and+receives+two+items
++++delegate(KeyValuePair<String,+Int32>+x,+KeyValuePair<String,+Int32>+y)+
++++{
++++++++//+returns+a+int+indicating+whether+the+items+are+"equal"+-+equal+being+what+is+implemented+it+the+appropriate+compare+function.
++++++++return+x.Value.CompareTo(y.Value);
++++}
++);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1931829|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>myList.Sort //Sort using a your own compare function
 (
 // declare the compare function, returns a int, and receives two items
 delegate(KeyValuePair&lt;String, Int32&gt; x, KeyValuePair&lt;String, Int32&gt; y) 
 {
 // returns a int indicating whether the items are "equal" - equal being what is implemented it the appropriate compare function.
 return x.Value.CompareTo(y.Value);
 }
 );
</code></pre>

blocks|key|1931892|text|这样想吧。假设你有一个看起来像这样的方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1931893|public+int+MyComparisonMethod(KeyValuePair<string,+int>+x,+KeyValuePair<string,int>+y)
{
+++return+x.Value.CompareTo(y.Value);
}|code-block|syntax|javascript|1931894|这基本上接受两个值，并对它们进行比较。它分别返回-1、0或1，这取决于x是否小于、等于或大于y。|1931895|现在，在幕后，List.Sort使用了快速排序算法。你所需要理解的就是，它会不断地将你列表中的各种元素相互比较。它如何知道值a是否大于、小于或等于值b？它调用此方法，并根据该方法获知。合乎道理?|1931896|所以这个想法是，你提供了一种机制来比较列表中的两个值，List.Sort使用它来进行排序所需的比较。|1931897|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Think about it this way. Say you had a method that looked like this:

<pre><code>public int MyComparisonMethod(KeyValuePair&lt;string, int&gt; x, KeyValuePair&lt;string,int&gt; y)
{
 return x.Value.CompareTo(y.Value);
}
</code></pre>

This basically takes two values, and compares them. It returns a -1 , 0 or 1 depending if x is less than, equal to or greater than y respectively.

Now, under the covers, List.Sort used the Quick Sort algorithm. All you need to understand is, that it keeps comparing various elements in your list against each other. How does it know if value a is greater than, less than or equal to value b? It calls this method, and based on that, it knows. Makes sense?

So the idea is, you provide a mechanism for comparing two values in your list, an the List.Sort uses that to do the comparisons it needs for sorting.

blocks|key|528949|text|仅供参考，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|528950|这通常用于需要对自定义类列表进行排序的情况。|528951|例如|528952|class+Student
{
++++int+rollID;
++++string+name;
}

List<Student>+students+=+new+List<Student>();

...

students.Sort(delegate(Student+x,+Student+y)+{+return+x.rollID.CompareTo(y.rollID);});|code-block|syntax|javascript|528953|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|N|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|O|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|P|8|@]|9|@]|A|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Just an FYI,

This is commonly used in the case you need to sort a list of custom classes.

For e.g.

<pre><code>class Student
{
 int rollID;
 string name;
}

List&lt;Student&gt; students = new List&lt;Student&gt;();

...

students.Sort(delegate(Student x, Student y) { return x.rollID.CompareTo(y.rollID);});
</code></pre>

blocks|key|524198|text|它是隐含的，但是你可能应该提到你的"myList“的声明。让我来为你写吧。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|524199|var+myList=new+List<KeyValuePair<string,+int>>();|code-block|syntax|javascript|524200|现在，它意味着这个列表中的每一项都是KeyValuePairstring，int的一个实例。|524201|现在，来回答你的问题。|524202|Sort方法的一个重载接受“比较”委托，该委托接受集合的两个项并返回一个整数。|524203|public+delegate+int+Comparison<T>(T+x,+T+y)|524204|本质上，您正在做的是创建一个匿名委托，它使用IComparable的"CompareTo“方法(string和int实现此接口)比较两个项(在您的示例中，您是按”Value“排序，甚至可以按”Key“排序)。|524205|IComparable.CompareTo返回一个整数(排序方法用来排列列表中的项目)，表示lhs小于(-1)、大于(1)或等于(0)+rhs。|524206|仅供参考:如果你使用的是C#+3.0，你甚至不需要匿名代理。您可以使用lambda表达式(这是定义匿名委托more?的一种简写方式)|offset|length|524207|例如：|524208|myList.Sort((x,+y)+=>+x.Value.CompareTo(y.Value));
//Sort+over+Value

myList.Sort((x,+y)+=>+x.Key.CompareTo(y.Key));
//Sort+over+key|524209|希望这个解释能有所帮助。|524210|entityMap|0|LINK|mutability|MUTABLE|url|http://msdn.microsoft.com/en-us/library/bb397687.aspx^0|0|0|0|0|0|0|0|0|1H|5|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|1C|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|1D|8|@]|9|@]|A|$]]|$1|K|3|L|5|6|7|1E|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|1F|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|1G|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1H|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1I|8|@]|9|@$U|1J|V|1K|1|1L]]|A|$]]|$1|W|3|X|5|6|7|1M|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|D|7|1N|8|@]|9|@]|A|$E|F]]|$1|10|3|11|5|6|7|1O|8|@]|9|@]|A|$]]|$1|12|3|-4|5|6|7|1P|8|@]|9|@]|A|$]]]|13|$14|$5|15|16|17|A|$18|19]]]]

It is implicit, but may be you should have mentioned the declaration of your "myList".
let me write it for you.

<pre><code>var myList=new List&lt;KeyValuePair&lt;string, int&gt;&gt;();
</code></pre>

Now, what it means is that each item in this list is an instance of KeyValuePair[string,int].

Now, coming to your question.

One of the overloads of Sort method accepts a "Comparison" delegate, which takes two items of a collection and returns an integer number. 

<pre><code>public delegate int Comparison&lt;T&gt;(T x, T y)
</code></pre>

Essentially, what you are doing is creating an anonymous delegate which compares two items (in your case, you are sorting on 'Value' you can even sort on 'Key') using the "CompareTo" method of IComparable (string and int implement this interface).

IComparable.CompareTo returns an integer (which is used by Sort method to arrange the items in your list) stating that lhs is less than (-1), greather than (1) or equal to (0) rhs.

FYI: In case you are working on C# 3.0, you dont even need anonymous delegate. You can use lambda expression instead (it is a shorthand to define anonymous delegate, <a href="http://msdn.microsoft.com/en-us/library/bb397687.aspx" rel="nofollow noreferrer">more?</a> )

eg:

<pre><code>myList.Sort((x, y) =&gt; x.Value.CompareTo(y.Value));
//Sort over Value

myList.Sort((x, y) =&gt; x.Key.CompareTo(y.Key));
//Sort over key
</code></pre>

Hope the explanation is helpful.

I just lifted this snippet from a website and it proved to be exactly the solution I needed for my particular problem. 

I have no idea what it is (particularly the delegate and return parts) and the source doesn't explain it. 

Hoping SO can enlighten me.

<pre><code>myList.Sort( delegate(KeyValuePair&lt;String, Int32&gt; x, KeyValuePair&lt;String, Int32&gt; y) 
 { 
 return x.Value.CompareTo(y.Value); 
 }
 );
</code></pre>

ok, this worked. what is it exactly?

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。

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我刚刚从一个网站上拿到了这段代码，事实证明它正是我解决特定问题所需要的。我不知道它是什么(特别是委托和返回部分)，源代码也没有解释它。希望如此可以给我启迪。myList.Sort( delegate(KeyValuePair<String, Int32> x, KeyValuePair<String, Int32> y) { retur

问好了，这起作用了。它到底是什么？
EN

回答 6

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问好了，这起作用了。它到底是什么？EN

回答 6

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问好了，这起作用了。它到底是什么？
EN