blocks|key|1069140|text|var+val+=+yyy.First().Value;
return+yyy.All(x=>x.Value+==+val)+?+val+:+otherValue;+|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1069141|我能想到的最干净的方式。您可以通过内联val来使其成为一行程序，但是First()将被计算n次，从而使执行时间加倍。|unstyled|1069142|要合并注释中指定的“空集”行为，只需在上述两行之前再添加一行即可：|1069143|if(yyy+==+null+%7C%7C+!yyy.Any())+return+otherValue;|1069144|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@]|9|@]|A|$]]|$1|G|3|H|5|F|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$B|C]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>var val = yyy.First().Value;
return yyy.All(x=&gt;x.Value == val) ? val : otherValue; 
</code></pre>

Cleanest way I can think of. You can make it a one-liner by inlining val, but First() would be evaluated n times, doubling execution time.

To incorporate the "empty set" behavior specified in the comments, you simply add one more line before the two above: 

<pre><code>if(yyy == null || !yyy.Any()) return otherValue;
</code></pre>

blocks|key|1069200|text|return+collection.All(i+=>+i+==+collection.First()))+
++++?+collection.First()+:+otherValue;.|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1069201|或者，如果您担心为每个元素执行First()+(这可能是一个合理的性能问题)：|unstyled|1069202|var+first+=+collection.First();
return+collection.All(i+=>+i+==+first)+?+first+:+otherValue;|1069203|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>return collection.All(i =&gt; i == collection.First())) 
 ? collection.First() : otherValue;.
</code></pre>

Or if you're worried about executing First() for each element (which could be a valid performance concern):

<pre><code>var first = collection.First();
return collection.All(i =&gt; i == first) ? first : otherValue;
</code></pre>

blocks|key|854807|text|public+int+GetResult(List<int>+list){
int+first+=+list.First();
return+list.All(x+=>+x+==+first)+?+first+:+SOME_OTHER_VALUE;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|854808|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>public int GetResult(List&lt;int&gt; list){
int first = list.First();
return list.All(x =&gt; x == first) ? first : SOME_OTHER_VALUE;
}
</code></pre>

blocks|key|1069313|text|虽然您当然可以使用现有的序列操作符构建这样的设备，但在这种情况下，我倾向于将此操作符编写为自定义序列操作符。类似于：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1069314|//+Returns+"other"+if+the+list+is+empty.
//+Returns+"other"+if+the+list+is+non-empty+and+there+are+two+different+elements.
//+Returns+the+element+of+the+list+if+it+is+non-empty+and+all+elements+are+the+same.
public+static+int+Unanimous(this+IEnumerable<int>+sequence,+int+other)
{
++++int?+first+=+null;
++++foreach(var+item+in+sequence)
++++{
++++++++if+(first+==+null)
++++++++++++first+=+item;
++++++++else+if+(first.Value+!=+item)
++++++++++++return+other;
++++}
++++return+first+??+other;
}|code-block|syntax|javascript|1069315|这非常清楚，简短，涵盖了所有情况，并且不会不必要地创建序列的额外迭代。|1069316|将其转换为适用于IEnumerable<T>的泛型方法作为练习。:-)|offset|length|style|CODE|1069317|entityMap^0|0|0|0|8|E|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|T|8|@$K|U|L|V|M|N]]|9|@]|A|$]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Though you certainly can build such a device out of existing sequence operators, I would in this case be inclined to write this one up as a custom sequence operator. Something like:

<pre><code>// Returns "other" if the list is empty.
// Returns "other" if the list is non-empty and there are two different elements.
// Returns the element of the list if it is non-empty and all elements are the same.
public static int Unanimous(this IEnumerable&lt;int&gt; sequence, int other)
{
 int? first = null;
 foreach(var item in sequence)
 {
 if (first == null)
 first = item;
 else if (first.Value != item)
 return other;
 }
 return first ?? other;
}
</code></pre>

That's pretty clear, short, covers all the cases, and does not unnecessarily create extra iterations of the sequence.

Making this into a generic method that works on <code>IEnumerable&lt;T&gt;</code> is left as an exercise. :-)

blocks|key|854948|text|对所有平等的人进行快速测试：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|854949|collection.Distinct().Count()+==+1|code-block|syntax|javascript|854950|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|$]]

Good quick test for all equal:

<pre><code>collection.Distinct().Count() == 1
</code></pre>

blocks|key|1069438|text|这可能太晚了，但基于Eric的答案，这是一个适用于值类型和引用类型的扩展：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1069439|public+static+partial+class+Extensions
{
++++public+static+Nullable<T>+Unanimous<T>(this+IEnumerable<Nullable<T>>+sequence,+Nullable<T>+other,+IEqualityComparer+comparer+=+null)++where+T+:+struct,+IComparable
++++{
++++++++object+first+=+null;
++++++++foreach(var+item+in+sequence)
++++++++{
++++++++++++if+(first+==+null)
++++++++++++++++first+=+item;
++++++++++++else+if+(comparer+!=+null+&&+!comparer.Equals(first,+item))
++++++++++++++++return+other;
++++++++++++else+if+(!first.Equals(item))
++++++++++++++++return+other;
++++++++}
++++++++return+(Nullable<T>)first+??+other;
++++}

++++public+static+T+Unanimous<T>(this+IEnumerable<T>+sequence,+T+other,+IEqualityComparer+comparer+=+null)++where+T+:+class,+IComparable
++++{
++++++++object+first+=+null;
++++++++foreach(var+item+in+sequence)
++++++++{
++++++++++++if+(first+==+null)
++++++++++++++++first+=+item;
++++++++++++else+if+(comparer+!=+null+&&+!comparer.Equals(first,+item))
++++++++++++++++return+other;
++++++++++++else+if+(!first.Equals(item))
++++++++++++++++return+other;
++++++++}
++++++++return+(T)first+??+other;
++++}
}|code-block|syntax|javascript|1069440|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|$]]

This may be late, but an extension that works for value and reference types alike based on Eric's answer:

<pre><code>public static partial class Extensions
{
 public static Nullable&lt;T&gt; Unanimous&lt;T&gt;(this IEnumerable&lt;Nullable&lt;T&gt;&gt; sequence, Nullable&lt;T&gt; other, IEqualityComparer comparer = null) where T : struct, IComparable
 {
 object first = null;
 foreach(var item in sequence)
 {
 if (first == null)
 first = item;
 else if (comparer != null &amp;&amp; !comparer.Equals(first, item))
 return other;
 else if (!first.Equals(item))
 return other;
 }
 return (Nullable&lt;T&gt;)first ?? other;
 }

 public static T Unanimous&lt;T&gt;(this IEnumerable&lt;T&gt; sequence, T other, IEqualityComparer comparer = null) where T : class, IComparable
 {
 object first = null;
 foreach(var item in sequence)
 {
 if (first == null)
 first = item;
 else if (comparer != null &amp;&amp; !comparer.Equals(first, item))
 return other;
 else if (!first.Equals(item))
 return other;
 }
 return (T)first ?? other;
 }
}
</code></pre>

blocks|key|1069484|text|使用LINQ的另一种选择：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1069485|var+set+=+new+HashSet<int>(values);
return+(1+==+set.Count)+?+values.First()+:+otherValue;|code-block|syntax|javascript|1069486|我发现使用HashSet<T>处理多达6,000个整数的列表比使用以下代码更快：|offset|length|style|CODE|1069487|var+value1+=+items.First();
return+values.All(v+=>+v+==+value1)+?+value1:+otherValue;|1069488|entityMap^0|0|0|5|A|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

An alternative to using LINQ:

<pre><code>var set = new HashSet&lt;int&gt;(values);
return (1 == set.Count) ? values.First() : otherValue;
</code></pre>

I have found using <code>HashSet&lt;T&gt;</code> is quicker for lists of up to ~ 6,000 integers compared with:

<pre><code>var value1 = items.First();
return values.All(v =&gt; v == value1) ? value1: otherValue;
</code></pre>

blocks|key|1069524|text|对上面的简化方法稍有不同。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1069525|var+result+=+yyy.Distinct().Count()+==+yyy.Count();|offset|length|style|CODE|1069526|entityMap^0|0|0|1F|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

A slight variation on the above simplified approach.

<code>var result = yyy.Distinct().Count() == yyy.Count();</code>

blocks|key|1069564|text|如果数组的类型为多维，如下图所示，那么我们必须在linq下面编写代码来检查数据。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1069565|例如:这里的元素是0，我正在检查所有的值是否为0。|1069566|ip1=|1069567|+++++0+0+0+0|code-block|syntax|javascript|1069568|+++++0+0+0+0|1069569|+++++0+0+0+0|1069570|+++++0+0+0+0++|1069571|++++var+value=ip1[0][0];++//got+the+first+index+value
++++var+equalValue+=+ip1.Any(x=>x.Any(xy=>xy.Equals()));++//check+with+all+elements+value+
++++if(equalValue)//returns+true+or+false++
++++{++
++++return+"Same+Numbers";++
++++}else{++
++++return+"Different+Numbers";+++
++++}|1069572|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|V|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|W|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|X|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|H|7|Y|8|@]|9|@]|A|$I|J]]|$1|M|3|N|5|H|7|Z|8|@]|9|@]|A|$I|J]]|$1|O|3|P|5|H|7|10|8|@]|9|@]|A|$I|J]]|$1|Q|3|R|5|H|7|11|8|@]|9|@]|A|$I|J]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

If a array is of type multidimension like below then we have to write below linq to check the data.

example: here elements are 0 and i am checking all values are 0 or not. 
ip1= 
 0 0 0 0 
 0 0 0 0 
 0 0 0 0 
 0 0 0 0 

<pre><code> var value=ip1[0][0]; //got the first index value
 var equalValue = ip1.Any(x=&gt;x.Any(xy=&gt;xy.Equals())); //check with all elements value 
 if(equalValue)//returns true or false 
 { 
 return "Same Numbers"; 
 }else{ 
 return "Different Numbers"; 
 }
</code></pre>

If all the items in a list have the same value, then I need to use that value, otherwise I need to use an “otherValue”. I can’t think of a simple and clear way of doing this. When the list is empty it should return the &quot;other&quot; value.
See also <a href="https://stackoverflow.com/questions/4390232/neat-way-to-write-loop-that-has-special-logic-for-the-first-item-in-a-collection">Neat way to write loop that has special logic for the first item in a collection.</a>

How to check if all list items have the same value and return it, or return an “otherValue” if they don’t?

如果列表中的所有项都有相同的值，那么我需要使用该值，否则我需要使用“otherValue”。我想不出一个简单明了的方法来做这件事。当列表为空时，它应该返回"other“值。另请参阅

问如何检查所有列表项是否都具有相同的值并返回它，如果不是，则返回“otherValue”？
EN

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问如何检查所有列表项是否都具有相同的值并返回它，如果不是，则返回“otherValue”？EN

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问如何检查所有列表项是否都具有相同的值并返回它，如果不是，则返回“otherValue”？
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