I believe that it&#39;s related to type inference and/or lambda generation (when type inference has to go in the opposite direction to normal), combined with overload resolution. Unfortunately, just supplying the type parameters doesn&#39;t help the situation (where it presumably still has to perform the type checking).

The following code, which should logically be the equivalent code from yours, after lambdas have been analyzed, compiles without issue:

	static void Main()
	{
		var x = Enumerable.Range(0, 1).Sum(a);
	}

	private static int a(int a)
	{
		return Enumerable.Range(0, 1).Sum(b);
	}
	private static int b(int b)
	{
		return Enumerable.Range(0, 1).Sum(c);
	}
	private static int c(int c)
	{
		return Enumerable.Range(0, 1).Sum(d);
	}
	private static int d(int d)
	{
		return Enumerable.Range(0, 1).Sum(e);
	}
	private static int e(int e)
	{
		return Enumerable.Range(0, 1).Sum(f);
	}
	private static int f(int f)
	{
		return Enumerable.Range(0, 1).Count(g);
	}
	private static bool g(int g)
	{
		return true;
	}

---

I believe Eric Lippert has posted before that type inference is one of the places in the C# compiler where (certain problems) may force the compiler to try to solve an NP-Complete problem and its only real strategy (as here) is brute force. If I can find the relevant references, I&#39;ll add them here.

---

The best reference I can find is [here](http://blogs.msdn.com/b/ericlippert/archive/2007/03/26/lambda-expressions-vs-anonymous-methods-part-four.aspx) where Eric&#39;s discussing the fact that it&#39;s the overload resolution work that causes the real cost - remember, [Enumerable.Sum](http://msdn.microsoft.com/en-us/library/system.linq.enumerable.sum.aspx) has 10 overloads that accept a lambda/method.


Suppose to have a class `Obj`:

    class Obj {
      int field;
    }

...and that you have a list of `Obj` instances, i.e. `List&lt;Obj&gt; lst`.

Now, how can I find with streams the sum of the values of the int fields `field` from the objects in list `lst` under a filtering criterion (e.g. for an object `o`, the criterion is `o.field &gt; 10`)?

Sum values from specific field of the objects in a list

Is there a difference between these two code segments:

    void f() {
        thread_local vector&lt;int&gt; V;
        V.clear();
        ... // use V as a temporary variable
    }

and

    void f() {
        static thread_local vector&lt;int&gt; V;
        V.clear();
        ... // use V as a temporary variable
    }

Backstory: originally I had a STATIC vector&lt;int&gt; V (for holding some intermediate values, it gets cleared every time I enter the function) and a single-threaded program. I want to turn the program into a multithreading one, so somehow I have to get rid of this static modifier. My idea is to turn every static into thread_local and not worry about anything else? Can this approach backfire?

Are C++11 thread_local variables automatically static?

Try to compile following code and you&#39;ll find that compiler takes &gt;3 GB of RAM (all free memory on my machine) and very long time to compile (actually I get IO exception after 10 minutes).

    using System;
    using System.Linq;
     
    public class Test
    {
    	public static void Main()
    	{
    		Enumerable.Range(0, 1).Sum(a =&gt;
    		Enumerable.Range(0, 1).Sum(b =&gt;
    		Enumerable.Range(0, 1).Sum(c =&gt;
    		Enumerable.Range(0, 1).Sum(d =&gt;
    		Enumerable.Range(0, 1).Sum(e =&gt;
    		Enumerable.Range(0, 1).Sum(f =&gt;
    		Enumerable.Range(0, 1).Count(g =&gt; true)))))));
    	}
    }

Can anybody explain this curious behavior?

&lt;pre&gt;CS Version:     Microsoft (R) Visual C# Compiler version 4.0.30319.17929
OS Name:        Microsoft Windows 7 Ultimate
OS Version:     6.1.7601 Service Pack 1 Build 7601&lt;/pre&gt;


![Memory Usage][1]

  [1]: http://i.stack.imgur.com/QWZn4.png

Why does the C# compiler go mad on this nested LINQ query?

Try to compile following code and you'll find that compiler takes >3 GB of RAM (all free memory on my machine) and very long time to compile (actually I get IO exception after 10 minutes).
<pre><code class="hljs language-ini">using System;
using System.Linq;
 
public class Test
{
	public static void Main()
	{
		Enumerable.Range(0, 1).Sum(a =>
		Enumerable.Range(0, 1).Sum(b =>
		Enumerable.Range(0, 1).Sum(c =>
		Enumerable.Range(0, 1).Sum(d =>
		Enumerable.Range(0, 1).Sum(e =>
		Enumerable.Range(0, 1).Sum(f =>
		Enumerable.Range(0, 1).Count(g => true)))))));
	}
}
</code></pre>
Can anybody explain this curious behavior?
<pre>CS Version: Microsoft (R) Visual C# Compiler version 4.0.30319.17929
OS Name: Microsoft Windows 7 Ultimate
OS Version: 6.1.7601 Service Pack 1 Build 7601</pre>
<img src="http://i.stack.imgur.com/QWZn4.png" alt="Memory Usage">

I consume an API which returns the string values like this:
&gt; `some-enum-value`

I try to put these values in an `enum` , since the default `StringEnumConverter` doesn&#39;t do what I want, which is to to decorate this Converter with some additional logic. 

How can I be sure that the values are *deserialized* correctly ?

The following code is my tryout to get this job done.
&lt;br&gt;
However the line
&gt; `reader = new JsonTextReader(new StringReader(cleaned));` 

breaks the whole thing since the `base.ReadJson` can&#39;t recognize the string as a JSON.

Is there a better way to do this without having to implement all the existing logic in a `StringEnumConverter`?
&lt;br&gt;
How could I fix my approach?

    public class BkStringEnumConverter : StringEnumConverter
    {
        public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
        {
            if (reader.TokenType == JsonToken.String)
            {
                var enumString = reader.Value.ToString();
                if (enumString.Contains(&quot;-&quot;))
                {
                    var cleaned = enumString.Split(&#39;-&#39;).Select(FirstToUpper).Aggregate((a, b) =&gt; a + b);
                    reader = new JsonTextReader(new StringReader(cleaned));
                }
            }
            return base.ReadJson(reader, objectType, existingValue, serializer);
        }

        private static string FirstToUpper(string input)
        {
            var firstLetter = input.ToCharArray().First().ToString().ToUpper();
            return string.IsNullOrEmpty(input)
                ? input
                : firstLetter + string.Join(&quot;&quot;, input.ToCharArray().Skip(1));
        }
    }

How to make JSON.NET StringEnumConverter use hyphen-separated casing

I want to use MessageBox for showing download errors in my WP8.1 app.

I added:

    using System.Windows;

but when I type:

    MessageBox.Show(&quot;&quot;);

I get error:

    &quot;The name &#39;MessageBox&#39; does not exist in the current context&quot;


In Object Browser I found that such class should exist and in &quot;Project-&gt;Add reference... -&gt;Assemblies-&gt;Framework&quot; is shown that all assemblies are referenced.



Do I miss something? Or is there another way how to show something like messagebox?

Universal Apps MessageBox: &quot;The name &#39;MessageBox&#39; does not exist in the current context&quot;

Just read this [fascinating article][1] about the 20x-200x slowdowns you can get on Intel CPUs with denormalized floats (floating point numbers very close to 0).

There is an option with SSE to round these off to 0, restoring performance when such floating point values are encountered. 

How do C# apps handle this? Is there an option to enable/disable `_MM_FLUSH_ZERO`?


  [1]: https://stackoverflow.com/a/9314926/1294758

How are denormalized floats handled in C#?

Basically, I just ran a scan of my computer with [Malwarebytes][1] (updated the definitions before running), and it said my &quot;helloworld&quot; program written in C# has a [trojan][2].

I know for a fact this is a false positive, as I only wrote the program 2-3 days ago and followed a small tutorial website to make the program that I trust. I am new to C#, but I can&#39;t see anything that would give a trojan warning at all.

![Malwarebytes report][3]

The program flags the executable, but not the source file.

    using System;

    namespace HelloWorldApplication
    {
        class HelloWorld
        {
            static void Main(string[] args)
            {
                Console.WriteLine(&quot;\n\tHello World!&quot;);
                Console.WriteLine(&quot;This is my first C# program.\nI&#39;m so proud of myself!&quot;);
                Console.WriteLine(&quot;\tTeehee!&quot;);
            }
        }
    }

This is the code, written in [Notepad++][4], and it is run from the command-line ([Cygwin][5], actually). Why does it flags this? Is it something that, as a budding C# programmer, I should know about?

  [1]: https://en.wikipedia.org/wiki/Malwarebytes%27_Anti-Malware
  [2]: http://en.wikipedia.org/wiki/Trojan_horse_%28computing%29
  [3]: http://i.stack.imgur.com/lVEtN.png
  [4]: http://en.wikipedia.org/wiki/Notepad++
  [5]: http://en.wikipedia.org/wiki/Cygwin


Malwarebytes gives trojan warning for basic C# &quot;Hello World!&quot; program

What is the difference between `TestInitialize` vs `ClassInitialize` in MSTest?  What are the pros cons of each?

I&#39;m under the impression that `TestInitialze` should run with EACH test, every time?  Is that correct?  And that `ClassInitialize` will run every time a new instance of any class?  

TestInitialize vs ClassInitialize

I have a base class that has a bool property which looks like this:

    public abstract class MyBaseClass
    {
         public bool InProgress { get; protected set; }
    }

I am inheriting it another class from it and trying to add InProgress as a delegate to the dictionary. But it throws me an error. This is how my Derived class looks like:

    public abstract class MyClass
    {
         Dictionary&lt;string, object&gt; dict = new Dictionary&lt;string, object&gt;();
         dict.Add(&quot;InProgress&quot;, InProgress =&gt; base.InProgress = InProgress);
    
    }

This is the error I am getting:

&gt; Cannot convert lambda expression to type &#39;object&#39; because it is not a delegate type

What am I doing wrong here?

Cannot convert lambda expression to type &#39;object&#39; because it is not a delegate type

I&#39;m using EF 6.0 with LINQ in MVC 5 project. I want to log all the SQL queries executed by the Entity Framework DbContext for debugging/performance-measurement purpose.

In Java/Hibernate, equivalent behavior can be achieved by setting the property `hibernate.show_sql=true`. Is it possible to have a similar behavior in Entity Framework?

Log Queries executed by Entity Framework DbContext

This error is happening in many of the files in my &quot;Views&quot; folder:

&gt; &#39;System.Collection.GenericList&lt;AssetMgrUser&gt;&#39; does not contain a
&gt; definition for &#39;Select&#39; accepting a first argument of type
&gt; &#39;System.Collections.GenericList&lt;AssetMgrUser&gt;&#39; could be found (are you
&gt; missing a using directive or an assembly reference?)

I&#39;ve tried adding a bunch of &quot;using System...&quot; and other basic libraries near the top of the file but adding those do not seem to help any.

This is where the error occurs for me is in the line that starts with `.BindTo(Model.Users.Select(o =&gt; o.UserName))`:

Any help would be greatly appreciated. Thanks!

     &lt;div id=&quot;editRolesContainer&quot; class=&quot;detailContainer detailContainer4&quot;&gt;
        &lt;header class=&quot;sectionheader&quot;&gt; Add Roles &lt;/header&gt;
        &lt;ul id = &quot;AdminSelectUserContainer&quot; &gt;
           &lt;li&gt;
              &lt;ul style=&quot;padding: 0 0 0 5px&quot;&gt;
                 &lt;li&gt;Select User : &lt;/li&gt;
                 &lt;li&gt;
                    @using (Html.BeginForm(&quot;srch_GetUserRoles&quot;, &quot;Admin&quot;,
                       new { view = &quot;Users_Roles&quot; }, FormMethod.Post,
                       new { name = &quot;srch_GetUserRoles&quot; }))
                    {
                       @(Html.Telerik().AutoComplete()
                              .Name(&quot;acx_SelectUser&quot;)
                              .BindTo(Model.Users.Select(o =&gt; o.UserName))
                                  .HtmlAttributes(new { type &quot;submit&quot;   })
                              .HtmlAttributes(new { @class = &quot;SearchBox&quot;})
                              .AutoFill(true)
                              .Filterable((filtering =&gt;
                                  {
                                     filtering.FilterMode(AutoCompleteFilterMode.Contains);
                                  }))
                      )
                    }
                 &lt;/li&gt;
                &lt;/ul&gt;
               ...
               ...
               &lt;/div&gt;

System.Collections.Generic.List does not contain a definition for &#39;Select&#39;

I tried to do a lot of research but I&#39;m more of a db guy - so even the explanation in the MSDN doesn&#39;t make any sense to me. Can anyone please explain, and provide some examples on what `Include()` statement does in the term of `SQL` query?

What does Include() do in LINQ?

I am working with .NET4.5 and VS2013, I have this query that gets `dynamic` result from db. 

    dynamic topAgents = this._dataContext.Sql(
        &quot;select t.create_user_id as \&quot;User\&quot;, sum(t.netamount) as \&quot;Amount\&quot; from transactiondetail t where t.update_date &gt; sysdate -7 group by t.create_user_id&quot;)
        .QueryMany&lt;dynamic&gt;();

Following statement fails with compilation error `Cannot use a lambda expression as an argument to a dynamically dispatched operation without first casting it to a delegate or expression tree type`
without even allowing me to run it

    topAgents.ToList().Select(agent =&gt; new
    {
        User = agent.User != null ? string.Format(&quot;{0}&quot;, agent.User).Replace(&quot;CORPNTGB\\&quot;, &quot;&quot;) : null,
        Amount = agent.Amount
    });

while this one with `foreach` works just fine.

    var data = new List&lt;List&lt;object&gt;&gt;();
    foreach (dynamic agent in topAgents)
    {
        data.Add(new List&lt;object&gt;
        {
            agent.User != null ? string.Format(&quot;{0}&quot;, agent.User).Replace(&quot;CORPNTGB\\&quot;, &quot;&quot;) : null,
            agent.Amount
        });
    }

In my eyes after I `topAgents.ToList()` they could be interpreted as equivalent, is it because I explicitly state that `var data = new List&lt;List&lt;object&gt;&gt;();` that second statement is allowed by compiler?

**Why doesn&#39;t compiler allow LINQ select, but allows for each`?**

Content Type	Original Author	Original Content on Stackoverflow
Question	Eugene D. Gubenkov	View Question on Stackoverflow
Solution 1 - C#	Damien_The_Unbeliever	View Answer on Stackoverflow

Why does the C# compiler go mad on this nested LINQ query?

C# Problem Overview

C# Solutions

Solution 1 - C#

Are C++11 thread_local variables automatically static?

Sum values from specific field of the objects in a list

Attributions