blocks|key|282387|text|你可以这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|282388|HashSet<int>+sentIDs+=+new+HashSet<int>(SentList.Select(s+=>+s.MsgID));

var+results+=+MsgList.Where(m+=>+!sentIDs.Contains(m.MsgID));|code-block|syntax|javascript|282389|这将返回在SentList中没有匹配ID的MsgList中的所有消息。|offset|length|style|CODE|282390|entityMap^0|0|0|5|8|L|7|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]]|$1|G|3|H|5|6|7|Q|8|@$I|R|J|S|K|L]|$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

You could do something like:

<pre><code>HashSet&lt;int&gt; sentIDs = new HashSet&lt;int&gt;(SentList.Select(s =&gt; s.MsgID));

var results = MsgList.Where(m =&gt; !sentIDs.Contains(m.MsgID));
</code></pre>

This will return all messages in <code>MsgList</code> which don't have a matching ID in <code>SentList</code>.

blocks|key|499233|text|好吧，你已经有了很好的答案，但它们大多是Lambda。更多的LINQ方法如下所示|type|unstyled|depth|inlineStyleRanges|entityRanges|data|499234|var+NotSentMessages+=
++++++++++++++++from+msg+in+MsgList
++++++++++++++++where+!SentList.Any(x+=>+x.MsgID+==+msg.MsgID)
++++++++++++++++select+msg;|code-block|syntax|javascript|499235|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|$]]

Well, you already have good answers, but they're most Lambda. A more LINQ approach would be like

<pre><code>var NotSentMessages =
 from msg in MsgList
 where !SentList.Any(x =&gt; x.MsgID == msg.MsgID)
 select msg;
</code></pre>

blocks|key|282552|text|你可以这样做，这是最快的过程|type|unstyled|depth|inlineStyleRanges|entityRanges|data|282553|Var+result+=+MsgList.Except(MsgList.Where(o+=>+SentList.Select(s+=>+s.MsgID).ToList().Contains(o.MsgID))).ToList();|code-block|syntax|javascript|282554|这将为您提供预期的输出。|282555|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

You can do like this,this is the quickest process

<pre><code>Var result = MsgList.Except(MsgList.Where(o =&gt; SentList.Select(s =&gt; s.MsgID).ToList().Contains(o.MsgID))).ToList();
</code></pre>

This will give you expected output.

blocks|key|282491|text|试一下，|type|unstyled|depth|inlineStyleRanges|entityRanges|data|282492|++public+class+Sent
{
++++public+int+MsgID;
++++public+string+Content;
++++public+int+Status;

}

public+class+Messages
{
++++public+int+MsgID;
++++public+string+Content;
}

++List<Sent>+SentList+=+new+List<Sent>()+{+new+Sent()+{+MsgID+=+1,+Content+=+"aaa",+Status+=+0+},+new+Sent()+{+MsgID+=+3,+Content+=+"ccc",+Status+=+0+}+};
++++++++++++List<Messages>+MsgList+=+new+List<Messages>()+{+new+Messages()+{+MsgID+=+1,+Content+=+"aaa"+},+new+Messages()+{+MsgID+=+2,+Content+=+"bbb"+},+new+Messages()+{+MsgID+=+3,+Content+=+"ccc"+},+new+Messages()+{+MsgID+=+4,+Content+=+"ddd"+},+new+Messages()+{+MsgID+=+5,+Content+=+"eee"+}};

++++++++++++int+[]+sentMsgIDs+=+SentList.Select(v+=>+v.MsgID).ToArray();
++++++++++++List<Messages>+result1+=+MsgList.Where(o+=>+!sentMsgIDs.Contains(o.MsgID)).ToList<Messages>();|code-block|syntax|javascript|282493|希望能有所帮助。|282494|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Try,

<pre><code> public class Sent
{
 public int MsgID;
 public string Content;
 public int Status;

}

public class Messages
{
 public int MsgID;
 public string Content;
}

 List&lt;Sent&gt; SentList = new List&lt;Sent&gt;() { new Sent() { MsgID = 1, Content = "aaa", Status = 0 }, new Sent() { MsgID = 3, Content = "ccc", Status = 0 } };
 List&lt;Messages&gt; MsgList = new List&lt;Messages&gt;() { new Messages() { MsgID = 1, Content = "aaa" }, new Messages() { MsgID = 2, Content = "bbb" }, new Messages() { MsgID = 3, Content = "ccc" }, new Messages() { MsgID = 4, Content = "ddd" }, new Messages() { MsgID = 5, Content = "eee" }};

 int [] sentMsgIDs = SentList.Select(v =&gt; v.MsgID).ToArray();
 List&lt;Messages&gt; result1 = MsgList.Where(o =&gt; !sentMsgIDs.Contains(o.MsgID)).ToList&lt;Messages&gt;();
</code></pre>

Hope it should help.

blocks|key|282609|text|作为一种扩展方法|type|unstyled|depth|inlineStyleRanges|entityRanges|data|282610|public+static+IEnumerable<TSource>+AreNotEqual<TSource,+TKey,+TTarget>(this+IEnumerable<TSource>+source,+Func<TSource,+TKey>+sourceKeySelector,+IEnumerable<TTarget>+target,+Func<TTarget,+TKey>+targetKeySelector)+
{
++++var+targetValues+=+new+HashSet<TKey>(target.Select(targetKeySelector));

++++return+source.Where(sourceValue+=>+targetValues.Contains(sourceKeySelector(sourceValue))+==+false);
}|code-block|syntax|javascript|282611|例如：|282612|public+class+Customer
{
++++public+int+CustomerId+{+get;+set;+}
}

public+class+OtherCustomer
{
++++public+int+Id+{+get;+set;+}
}


var+customers+=+new+List<Customer>()
{
++++new+Customer()+{+CustomerId+=+1+},
++++new+Customer()+{+CustomerId+=+2+}
};

var+others+=+new+List<OtherCustomer>()
{
++++new+OtherCustomer()+{+Id+=+2+},
++++new+OtherCustomer()+{+Id+=+3+}
};

var+result+=+customers.AreNotEqual(customer+=>+customer.CustomerId,+others,+other+=>+other.Id).ToList();

Debug.Assert(result.Count+==+1);
Debug.Assert(result[0].CustomerId+==+1);|282613|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|$]]

As an extension method

<pre><code>public static IEnumerable&lt;TSource&gt; AreNotEqual&lt;TSource, TKey, TTarget&gt;(this IEnumerable&lt;TSource&gt; source, Func&lt;TSource, TKey&gt; sourceKeySelector, IEnumerable&lt;TTarget&gt; target, Func&lt;TTarget, TKey&gt; targetKeySelector) 
{
 var targetValues = new HashSet&lt;TKey&gt;(target.Select(targetKeySelector));

 return source.Where(sourceValue =&gt; targetValues.Contains(sourceKeySelector(sourceValue)) == false);
}
</code></pre>

eg.

<pre><code>public class Customer
{
 public int CustomerId { get; set; }
}

public class OtherCustomer
{
 public int Id { get; set; }
}


var customers = new List&lt;Customer&gt;()
{
 new Customer() { CustomerId = 1 },
 new Customer() { CustomerId = 2 }
};

var others = new List&lt;OtherCustomer&gt;()
{
 new OtherCustomer() { Id = 2 },
 new OtherCustomer() { Id = 3 }
};

var result = customers.AreNotEqual(customer =&gt; customer.CustomerId, others, other =&gt; other.Id).ToList();

Debug.Assert(result.Count == 1);
Debug.Assert(result[0].CustomerId == 1);
</code></pre>

blocks|key|499387|text|List<Person>+persons1+=+new+List<Person>
+++++++++++{
++++++++++++++++++++new+Person+{Id+=+1,+Name+=+"Person+1"},
++++++++++++++++++++new+Person+{Id+=+2,+Name+=+"Person+2"},
++++++++++++++++++++new+Person+{Id+=+3,+Name+=+"Person+3"},
++++++++++++++++++++new+Person+{Id+=+4,+Name+=+"Person+4"}
+++++++++++};


++++++++List<Person>+persons2+=+new+List<Person>
+++++++++++{
++++++++++++++++++++new+Person+{Id+=+1,+Name+=+"Person+1"},
++++++++++++++++++++new+Person+{Id+=+2,+Name+=+"Person+2"},
++++++++++++++++++++new+Person+{Id+=+3,+Name+=+"Person+3"},
++++++++++++++++++++new+Person+{Id+=+4,+Name+=+"Person+4"},
++++++++++++++++++++new+Person+{Id+=+5,+Name+=+"Person+5"},
++++++++++++++++++++new+Person+{Id+=+6,+Name+=+"Person+6"},
++++++++++++++++++++new+Person+{Id+=+7,+Name+=+"Person+7"}
+++++++++++};
++++++++var+output+=+(from+ps1+in+persons1
++++++++++++++++++++++from+ps2+in+persons2
++++++++++++++++++++++where+ps1.Id+==+ps2.Id
++++++++++++++++++++++select+ps2.Name).ToList();|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|499388|Person类|unstyled|499389|public+class+Person
{++++++++
++++public+int+Id+{+get;+set;+}+++++++

++++public+string+Name+{+get;+set;+}
}|499390|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>List&lt;Person&gt; persons1 = new List&lt;Person&gt;
 {
 new Person {Id = 1, Name = "Person 1"},
 new Person {Id = 2, Name = "Person 2"},
 new Person {Id = 3, Name = "Person 3"},
 new Person {Id = 4, Name = "Person 4"}
 };


 List&lt;Person&gt; persons2 = new List&lt;Person&gt;
 {
 new Person {Id = 1, Name = "Person 1"},
 new Person {Id = 2, Name = "Person 2"},
 new Person {Id = 3, Name = "Person 3"},
 new Person {Id = 4, Name = "Person 4"},
 new Person {Id = 5, Name = "Person 5"},
 new Person {Id = 6, Name = "Person 6"},
 new Person {Id = 7, Name = "Person 7"}
 };
 var output = (from ps1 in persons1
 from ps2 in persons2
 where ps1.Id == ps2.Id
 select ps2.Name).ToList();
</code></pre>

Person class

<pre><code>public class Person
{ 
 public int Id { get; set; } 

 public string Name { get; set; }
}
</code></pre>

blocks|key|282675|text|如果你想从第二个列表中选择列表中的项目：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|282676|MainList.Where(p+=>+2ndlist.Contains(p.columns+from+MainList+)).ToList()；|282677|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

If u wanna Select items of List from 2nd list:
MainList.Where(p =&gt; 2ndlist.Contains(p.columns from MainList )).ToList();

blocks|key|282413|text|List<Car>+cars+=+new+List<Car>()+{++new+Car()+{+Name+=+"Ford",+Year+=+1892,+Website+=+"www.ford.us"+},+
++++++++++++++++++++++++++++++++++++new+Car()+{+Name+=+"Jaguar",+Year+=+1892,+Website+=+"www.jaguar.co.uk"+},+
++++++++++++++++++++++++++++++++++++new+Car()+{+Name+=+"Honda",+Year+=+1892,+Website+=+"www.honda.jp"}+};

List<Factory>+factories+=+new+List<Factory>()+{+++++new+Factory()+{+Name+=+"Ferrari",+Website+=+"www.ferrari.it"+},+
++++++++++++++++++++++++++++++++++++++++++++++++++++new+Factory()+{+Name+=+"Jaguar",+Website+=+"www.jaguar.co.uk"+},+
++++++++++++++++++++++++++++++++++++++++++++++++++++new+Factory()+{+Name+=+"BMW",+Website+=+"www.bmw.de"}+};

foreach+(Car+car+in+cars.Where(c+=>+!factories.Any(f+=>+f.Name+==+c.Name)))+{
++++lblDebug.Text+%2B=+car.Name;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|282414|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>List&lt;Car&gt; cars = new List&lt;Car&gt;() { new Car() { Name = "Ford", Year = 1892, Website = "www.ford.us" }, 
 new Car() { Name = "Jaguar", Year = 1892, Website = "www.jaguar.co.uk" }, 
 new Car() { Name = "Honda", Year = 1892, Website = "www.honda.jp"} };

List&lt;Factory&gt; factories = new List&lt;Factory&gt;() { new Factory() { Name = "Ferrari", Website = "www.ferrari.it" }, 
 new Factory() { Name = "Jaguar", Website = "www.jaguar.co.uk" }, 
 new Factory() { Name = "BMW", Website = "www.bmw.de"} };

foreach (Car car in cars.Where(c =&gt; !factories.Any(f =&gt; f.Name == c.Name))) {
 lblDebug.Text += car.Name;
}
</code></pre>

i have a two list

<pre><code>List&lt;Sent&gt; SentList;
List&lt;Messages&gt; MsgList;
</code></pre>

both have the same property called MsgID;

<pre><code>MsgList SentList 

MsgID Content MsgID Content Stauts
1 aaa 1 aaa 0
2 bbb 3 ccc 0
3 ccc 
4 ddd
5 eee
</code></pre>

i want to compare the MsgID in Msglist with the sentlist and need items which are not in the sent list using linq

<pre><code>Result 

MsgID Content
2 bbb
4 ddd
5 eee
</code></pre>

compare two list and return not matching items using linq

我有两张单子List<Sent> SentList;List<Messages> MsgList;两者都具有相同的属性，称为MsgID；MsgList SentList MsgID Content MsgID Content Stauts1 aaa 1 aaa 02 bbb 3 c

问使用linq比较两个列表并返回不匹配的项目
EN

回答 8

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问使用linq比较两个列表并返回不匹配的项目EN

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问使用linq比较两个列表并返回不匹配的项目
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