You&#39;ll need to use escape sequences like you would for any XML document, which is all the .config files are.

 - Ampersand = &amp; = `&amp;amp;`
 - Greater Than = &gt; = `&amp;gt;`
 - Less Than = &lt; = `&amp;lt;`
 - Apostrophe = &#39; = `&amp;apos;`
 - Quote = &quot; = `&amp;quot;`

You can also use the `CDATA` tag so that you can use these illegal characters

`&lt;![CDATA[` and ends with `]]&gt;`

    &lt;connectionStrings&gt;
        &lt;add name=&quot;MyEntities&quot; connectionString=&quot;
            metadata=res://*/MyDataModel.csdl|res://*/MyDataModel.ssdl|res://*/MyDataModel.msl;
            provider=System.Data.SqlClient;
            provider connection string=&amp;quot;
            Data Source=localhost\DEV;
            Initial Catalog=MyDB;UserId=myUser;
            Password=&lt;![CDATA[jack&amp;jill]]&gt;;
            MultipleActiveResultSets=True&amp;quot;&quot; 
            providerName=&quot;System.Data.EntityClient&quot; /&gt;
    &lt;/connectionStrings&gt;

I&#39;m building a website using Django. The website could have a significant number of users from non-English speaking countries.

I just want to know if there are any technical restrictions on what types of characters an email address could contain.

Are email addresses only allowed to contain English letters, numbers, `_`, `@` and `.`?

Are they allowed to contain non-English alphabets like `&#233;` or `&#252;`?

Are they allowed to contain Chinese or Japanese or other Unicode characters?

Are email addresses allowed to contain non-alphanumeric characters?

I have an asp.net application, and now I am using datasets for data manipulation. I recently started to convert this dataset to a List collection. But, in some places it doesn&#39;t work. One is that in my old version I am using `datarow[] drow =  dataset.datatable.select(searchcriteria)`. But in the List collection there is no method available for finding particular values. Is there any way for me to select some values according with my search criteria? I want to know if this is possible. Please help me.


Select method in List&lt;t&gt; Collection

I&#39;m using Entity Framework 4 for a simple app and would like to bake my connection credentials into the following connection string:

    &lt;connectionStrings&gt;
        &lt;add name=&quot;MyEntities&quot;    
             connectionString=&quot;metadata=res://*/MyDataModel.csdl|res://*/MyDataModel.ssdl|res://*/MyDataModel.msl;provider=System.Data.SqlClient;provider connection string=&amp;quot;Data Source=localhost\DEV;Initial Catalog=MyDB;UserId=myUser;Password=jack&amp;jill;MultipleActiveResultSets=True&amp;quot;&quot; 
             providerName=&quot;System.Data.EntityClient&quot; /&gt;
    &lt;/connectionStrings&gt;

However, the password (which I cannot change) contains an ampersand.  ASP.NET throws:
`Configuration Error: An error occurred while parsing EntityName. Line XX, position YYY.`

If I replace the ampersand in the password with `&amp;amp;`, I get a `SqlException: Login failed for user &#39;myUser&#39;. `  Usually this trick works, but I&#39;m guessing that something is failing because this is technically a connection string inside a connection string.

What should I do here?  Most of my classes include code like:

    using (var context = new MyEntities()) {
       // do work
    }

----------

**Update:**  It turns out that the credentials I am using are a domain account, so what I really need is `Integrated Security=True` in the connection string rather than a password.

Encoding the ampersand as indicated in the accepted answer *should* work fine, though I haven&#39;t tested it.




How to include ampersand in connection string?

I'm using Entity Framework 4 for a simple app and would like to bake my connection credentials into the following connection string:
<pre><code class="hljs language-ini">&#x3C;connectionStrings>
 &#x3C;add name="MyEntities" 
 connectionString="metadata=res://*/MyDataModel.csdl|res://*/MyDataModel.ssdl|res://*/MyDataModel.msl;provider=System.Data.SqlClient;provider connection string=&#x26;quot;Data Source=localhost\DEV;Initial Catalog=MyDB;UserId=myUser;Password=jack&#x26;jill;MultipleActiveResultSets=True&#x26;quot;" 
 providerName="System.Data.EntityClient" />
&#x3C;/connectionStrings>
</code></pre>
However, the password (which I cannot change) contains an ampersand. ASP.NET throws:
<code>Configuration Error: An error occurred while parsing EntityName. Line XX, position YYY.</code>
If I replace the ampersand in the password with <code>&#x26;amp;</code>, I get a <code>SqlException: Login failed for user 'myUser'. </code> Usually this trick works, but I'm guessing that something is failing because this is technically a connection string inside a connection string.
What should I do here? Most of my classes include code like:
<pre><code class="hljs language-csharp">using (var context = new MyEntities()) {
 // do work
}
</code></pre>
<hr>
Update: It turns out that the credentials I am using are a domain account, so what I really need is <code>Integrated Security=True</code> in the connection string rather than a password.
Encoding the ampersand as indicated in the accepted answer should work fine, though I haven't tested it.

Yes is a most frequent question, and this matter is vague for me and since I don&#39;t know much about it.

But i would like a very precise way to find a files Encoding.
So precise as Notepad++ is.


Effective way to find any file&#39;s Encoding

I was just simply wondering how I could limit the length of a string in C#.

    string foo = &quot;1234567890&quot;;
Say we have that. How can I limit foo to say, 5 characters?

C#: Limit the length of a string?

Is there anything built into `System.IO.Path` that gives me just the filepath?

For example, if I have a `string` 

&gt; @&quot;c:\webserver\public\myCompany\configs\promo.xml&quot;,

 

is there any BCL method that will give me 

&gt; &quot;c:\webserver\public\myCompany\configs\&quot;?

Get full path without filename from path that includes filename

**Important Update: See update 5 at the bottom there is no performance issue in asp.net mvc 3, this is a benchmark issue**


I&#39;ve made a simple hello world project in asp.net mvc2,3 aspx and 3 razor and benchmarked them. What I see is:

    System                  Requests per second
    -------------------------------------------
    asp.net mvc 2 ASPX                     4200
    asp.net mvc 3 Beta 1 ASPX              3200
    asp.net mvc 3 Beta 1 Razor             1700

What&#39;s wrong with razor, it&#39;s so slow?

**Update:**
I&#39;ve redone the test. All 4 test virtual directories uses the same .net 4 integrated mode app pool. All projects are done with add new empty x project and adding 1 page with 1 line text and with no code. all sites are compiled in release mode. My system is windows 7, 4 gb i7 4 cores. I&#39;ve run the test 2 times to warm up iis and these are second run results. apache bench parameters : ab -n100000 -c1000 
results:

    System         Requests per second   CPU Utilization
    ----------------------------------------------------
    asp.net 4                     4780               43%
    mcv 2                         4322               58%
    mvc 3 beta 1 aspx             2324               54%
    mvc 3 beta 1 razor            1615               54%

**Update 2** Scott Guthrie answered in his blog:

&gt; *We haven&#39;t fully optimized MVC3 yet (there is usually a lot of cache tuning we do).  We expect razor to be the same performance as the .aspx view engine before it is finally released.*

    System         Requests per second   CPU Utilization
    ----------------------------------------------------
    mvc 3 rc1 razor               1960               54%
    mvc 3 rc2 razor               2187               54%
    mvc 3 rc2 aspx                4014               58%


**Update 5** all tests done in release mode but, the problem was `debug=&quot;true&quot;` in my web.config file (that also effects release builds), after change it to false, issue fixed. And it&#39;s interesting how it&#39;s effecting only razor templating at this scale. This should be in our mind on deployments.

    System         Requests per second   CPU Utilization
    ----------------------------------------------------
    mvc 3 rc2 razor               3940               58%
    mvc 3 rc2 aspx                4100               58%

Thanks to asp.net mvc team, excellent job!

ASP.NET MVC 3 Razor performance

Is there a standard message box in WPF, like WinForms&#39; [`System.Windows.Forms.MessageBox.Show()`](https://msdn.microsoft.com/en-us/library/system.windows.forms.messagebox.aspx), or should I use the WinForms message box?

Is there a MessageBox equivalent in WPF?

I am experiencing a request timeout from IIS when I run a long operation. Behind the scene my ASP.NET application is processing data, but the number of records being processed is large, and thus the operation is taking a long time. 

However, I think IIS times out the session. Is this a problem with IIS or ASP.NET session?


IIS Request Timeout on long ASP.NET operation

I am getting the error **Maximum request length exceeded** when I am trying to upload a video in my site.  

How do I fix this?

Maximum request length exceeded.

How can I add and read the value from **web.config** file?

Read Variable from Web.Config

We (our IT partner really) recently changed some DNS for a web farmed site we have, so that the two production server have round-robin DNS switching between them. Prior to this switch we didn&#39;t really have problems with `WebResource.axd` files. Since the switch, when we hit the live public URL, we get an error:

&gt; CryptographicException 
&gt;
&gt; Padding is invalid and cannot be removed.

When we hit the specific servers themselves, they load fine. I&#39;ve researched the issue and it seems since they&#39;re sharing assets between two servers, we need to have a consistent `machineKey` in the `web.config` for each server so they can encrypt and decrypt consistently between the two. My questions are:

1. Can I generate a `machineKey` via a tool on the server, or do I need to write code to do this?
2. Do I just need to add the `machineKey` to the `web.config` on each server or do you think I&#39;ll need to do anything else to make the two server work together? (Both `web.config`&#39;s currently do not have a `machineKey`)

Adding machineKey to web.config on web-farm sites

anybody how can I know if the request is ajax ? (I&#39;m using jquery for ajax)

how to know if the request is ajax in asp.net mvc?

Can anyone recommend a Unix (choose your flavor) JSON parser that could be used to introspect values from a JSON response in a pipeline?

Unix command-line JSON parser?

I am trying to implement a custom configuration section in a project and I keep running up against exceptions that I do not understand. I am hoping someone can fill in the blanks here. 

I have `App.config` that looks like this: 

&lt;!-- language: lang-xml --&gt;

    &lt;?xml version=&quot;1.0&quot; encoding=&quot;utf-8&quot; ?&gt;
    &lt;configuration&gt;
    	&lt;configSections&gt;
    		&lt;section name=&quot;ServicesSection&quot; type=&quot;RT.Core.Config.ServicesConfigurationSectionHandler, RT.Core&quot;/&gt;
    	&lt;/configSections&gt;
    	&lt;ServicesSection type=&quot;RT.Core.Config.ServicesSection, RT.Core&quot;&gt;
    			&lt;Services&gt;
    				&lt;AddService Port=&quot;6996&quot; ReportType=&quot;File&quot; /&gt;
    				&lt;AddService Port=&quot;7001&quot; ReportType=&quot;Other&quot; /&gt;
    			&lt;/Services&gt;
    		&lt;/ServicesSection&gt;
    &lt;/configuration&gt;

I have a `ServiceConfig` element defined like so: 

    public class ServiceConfig : ConfigurationElement
      {
        public ServiceConfig() {}
    
        public ServiceConfig(int port, string reportType)
        {
          Port = port;
          ReportType = reportType;
        }
    
        [ConfigurationProperty(&quot;Port&quot;, DefaultValue = 0, IsRequired = true, IsKey = true)]
        public int Port 
        {
          get { return (int) this[&quot;Port&quot;]; }
          set { this[&quot;Port&quot;] = value; }
        }
    
        [ConfigurationProperty(&quot;ReportType&quot;, DefaultValue = &quot;File&quot;, IsRequired = true, IsKey = false)]
        public string ReportType
        {
          get { return (string) this[&quot;ReportType&quot;]; }
          set { this[&quot;ReportType&quot;] = value; }
        }
      }

And I have a `ServiceCollection` defined like so: 

    public class ServiceCollection : ConfigurationElementCollection
      {
        public ServiceCollection()
        {
          Console.WriteLine(&quot;ServiceCollection Constructor&quot;);
        }
    
        public ServiceConfig this[int index]
        {
          get { return (ServiceConfig)BaseGet(index); }
          set
          {
            if (BaseGet(index) != null)
            {
              BaseRemoveAt(index);
            }
            BaseAdd(index, value);
          }
        }
    
        public void Add(ServiceConfig serviceConfig)
        {
          BaseAdd(serviceConfig);
        }
    
        public void Clear()
        {
          BaseClear();
        }
    
        protected override ConfigurationElement CreateNewElement()
        {
          return new ServiceConfig();
        }
    
        protected override object GetElementKey(ConfigurationElement element)
        {
          return ((ServiceConfig) element).Port;
        }
    
        public void Remove(ServiceConfig serviceConfig)
        {
          BaseRemove(serviceConfig.Port);
        }
    
        public void RemoveAt(int index)
        {
          BaseRemoveAt(index);
        }
    
        public void Remove(string name)
        {
          BaseRemove(name);
        }
      }

The part I am missing is what to do for the handler. Originally, I tried to implement an `IConfigurationSectionHandler` but found two things:

1. it didn&#39;t work
2. it&#39;s deprecated. 

I&#39;m completely lost now on what to do so I can read my data from config. Any help please!



How to implement a ConfigurationSection with a ConfigurationElementCollection

I&#39;m trying to implement Git to manage creative assets (Photoshop, Illustrator, Maya, etc.), and I&#39;d like to exclude files from Git based on file size rather than extension, location, etc.

For example, I don&#39;t want to exclude all .avi files, but there are a handful of massive +1GB avi files in random directories that I don&#39;t want to commit. 

Any suggestions?

gitignore by file size?

I must admit, that usually I haven&#39;t bothered switching between the *Debug* and *Release* configurations in my program, and I have usually opted to go for the *Debug* configuration, even when the programs are actually deployed at the customers place.

As far as I know, the only difference between these configurations if you don&#39;t change it manually is that *Debug* have the **`DEBUG`** constant defined, and *Release* have the *Optimize code* checked of.

So my questions is actually twofold:

1. Are there much performance differences between these two configurations. Are there any specific type of code that will cause big differences in performance here, or is it actually not that important?

2. Are there any type of code that will run fine under the *Debug* configuration that might fail under *Release* configuration, or can you be certain that code that is tested and working fine under the *Debug* configuration will also work fine under Release configuration.

Performance differences between debug and release builds

I would like to make vim my C++ editor. I have very little experience working with it 
and need help in configuring vim to work with C++.
I need such features as 
 
* code-complete (for stl and for my classes)
* switching between .cc and .h files
* may be some more tricks you, C++ and vim gurus, have.

May be you could provide some configs (with explanations), or links to tutorials, plugins I could make use of?


Configuring Vim for C++

This isn&#39;t a case-sensitive comparison in LINQ&amp;nbsp;to&amp;nbsp;Entities:

    Thingies.First(t =&gt; t.Name == &quot;ThingamaBob&quot;);

How can I achieve case sensitive comparison with LINQ&amp;nbsp;to&amp;nbsp;Entities?


LINQ to Entities case sensitive comparison

Just curious as to how Skip &amp; Take are supposed to work. I&#39;m getting the results I want to see on the client side, but when I hook up the AnjLab SQL Profiler and look at the SQL that is being executed it looks as though it is querying for and returning the entire set of rows to the client.

Is it really returning all the rows then sorting and narrowing down stuff with LINQ on the client side?

I&#39;ve tried doing it with both Entity Framework and Linq to SQL; both appear to have the same behavior.

Not sure it makes any difference, but I&#39;m using C# in VWD 2010.

Any insight?

    public IEnumerable&lt;Store&gt; ListStores(Func&lt;Store, string&gt; sort, bool desc, int page, int pageSize, out int totalRecords)
    {
    	var context = new TectonicEntities();
    	totalRecords = context.Stores.Count();
    	int skipRows = (page - 1) * pageSize;
    	if (desc)
    		return context.Stores.OrderByDescending(sort).Skip(skipRows).Take(pageSize).ToList();
    	return context.Stores.OrderBy(sort).Skip(skipRows).Take(pageSize).ToList();
    }

Resulting SQL (Note: I&#39;m excluding the Count query):

    SELECT 
    [Extent1].[ID] AS [ID], 
    [Extent1].[Name] AS [Name], 
    [Extent1].[LegalName] AS [LegalName], 
    [Extent1].[YearEstablished] AS [YearEstablished], 
    [Extent1].[DiskPath] AS [DiskPath], 
    [Extent1].[URL] AS [URL], 
    [Extent1].[SecureURL] AS [SecureURL], 
    [Extent1].[UseSSL] AS [UseSSL]
    FROM [dbo].[tec_Stores] AS [Extent1]

After some further research, I found that the following works the way I would expect it to:

    public IEnumerable&lt;Store&gt; ListStores(Func&lt;Store, string&gt; sort, bool desc, int page, int pageSize, out int totalRecords)
    {
    	var context = new TectonicEntities();
    	totalRecords = context.Stores.Count();
    	int skipRows = (page - 1) * pageSize;			
    	var qry = from s in context.Stores orderby s.Name ascending select s;
    	return qry.Skip(skipRows).Take(pageSize);			
    }

Resulting SQL:

    SELECT TOP (3) 
    [Extent1].[ID] AS [ID], 
    [Extent1].[Name] AS [Name], 
    [Extent1].[LegalName] AS [LegalName], 
    [Extent1].[YearEstablished] AS [YearEstablished], 
    [Extent1].[DiskPath] AS [DiskPath], 
    [Extent1].[URL] AS [URL], 
    [Extent1].[SecureURL] AS [SecureURL], 
    [Extent1].[UseSSL] AS [UseSSL]
    FROM ( SELECT [Extent1].[ID] AS [ID], [Extent1].[Name] AS [Name], [Extent1].[LegalName] AS [LegalName], [Extent1].[YearEstablished] AS [YearEstablished], [Extent1].[DiskPath] AS [DiskPath], [Extent1].[URL] AS [URL], [Extent1].[SecureURL] AS [SecureURL], [Extent1].[UseSSL] AS [UseSSL], row_number() OVER (ORDER BY [Extent1].[Name] ASC) AS [row_number]
    	FROM [dbo].[tec_Stores] AS [Extent1]
    )  AS [Extent1]
    WHERE [Extent1].[row_number] &gt; 3
    ORDER BY [Extent1].[Name] ASC

I really like the way the first option works; Passing in a lambda expression for sort. Is there any way to accomplish the same thing in the LINQ to SQL orderby syntax?  I tried using qry.OrderBy(sort).Skip(skipRows).Take(pageSize), but that ended up giving me the same results as my first block of code. Leads me to believe my issues are somehow tied to OrderBy.

====================================
PROBLEM SOLVED
====================================

Had to wrap the incoming lambda function in Expression: 

    Expression&lt;Func&lt;Store,string&gt;&gt; sort

Entity Framework/Linq to SQL: Skip &amp; Take

I have been working with Entity Framework 4 recently, and am slightly confused as to when to use [ObjectSet.Attach][1], and [ObjectSet.AddObject][2].

From my understanding:

- Use &quot;Attach&quot; when an Entity already exists in the system
- Use &quot;AddObject&quot; when creating a brand new Entity

So, if i&#39;m **creating a new Person**, i do this.

    var ctx = new MyEntities();
    var newPerson = new Person { Name = &quot;Joe Bloggs&quot; };
    ctx.Persons.AddObject(newPerson);
    ctx.SaveChanges();

If i&#39;m **modifying an existing Person**, i do this:

    var ctx = new MyEntities();
    var existingPerson = ctx.Persons.SingleOrDefault(p =&gt; p.Name = &quot;Joe Bloggs&quot; };
    existingPerson.Name = &quot;Joe Briggs&quot;;
    ctx.SaveChanges();

Keep in mind, this is a **very simple** example. In reality i am using Pure POCO&#39;s (no code generation), Repository pattern (don&#39;t deal with ctx.Persons), and Unit of Work (don&#39;t deal with ctx.SaveChanges). But &quot;under the covers&quot;, the above is what happens in my implementation.

**Now, my question** - I am yet to find a scenario where i have had to use **Attach**.

What am i missing here? When do we need to use Attach?

**EDIT**

Just to clarify, i&#39;m looking for *examples* of when to use Attach over AddObject (or vice-versa).

**EDIT 2**

The below answer is correct (which i accepted), but thought i&#39;d add another example where Attach would be useful.

In my above example for **modifying an existing Person**, two queries are actually being executed.

One to retrieve the Person (.SingleOrDefault), and another to perform the UPDATE (.SaveChanges).

If (for some reason), i already knew that &quot;Joe Bloggs&quot; existed in the system, why do an extra query to get him first? I could do this:

    var ctx = new MyEntities();
    var existingPerson = new Person { Name = &quot;Joe Bloggs&quot; };
    ctx.Persons.Attach(existingPerson);
    ctx.SaveChanges();

This will result in just an UPDATE statement being executed.

  [1]: http://msdn.microsoft.com/en-us/library/dd487214.aspx
  [2]: http://msdn.microsoft.com/en-us/library/dd487277.aspx

Entity Framework 4 - AddObject vs Attach

I generated an Entity Framework Model (4.0) from my database. I did not design the database and do not have any control over the schema, but there are a few tables that do not have foreign key constraints defined, but there is an implicit relationship defined.

For example:

I have a table called People that has the following columns:
GenderID
RaceID

There are tables for both Gender and Race but there is no foreign key in the People table.

When I imported the model it did not add Navigation Properties for these relationships. I tried to add it manually but From Role and To Role are disabled. I&#39;m not sure how to add the relationship myself. How do I do this?

Entity Framework - Add Navigation Property Manually

I have the following EF query:

    TestEntities db = new TestEntities();
    var questions = from q in db.Questions.Include(&quot;QuestionType&quot;)
                    from sq in db.SurveyQuestions
                    where sq.Survey == surveyTypeID
                    orderby sq.Order
                    select q;

    foreach( var question in questions ) {
        // ERROR: Null Reference Exception
        Console.WriteLine(&quot;Question Type: &quot; + question.QuestionType.Description);
    }
      
I am getting a null reference exception when I access the QuestionType property. I am using Include(&quot;QuestionType&quot;) but it doesn&#39;t appear to be working. What am I doing wrong?

**Edit**: It does not throw a null reference exception when I have Lazy Loading turned on.

**Edit**: Include() seems to be working when i do the following:

    var questions = db.Questions.Include(&quot;QuestionType&quot;).Select(q =&gt; q);

When I predicate on a separate entity Include seems to fail. Is that not allowed when using Include? What about my query is causing this thing to not work?

Content Type	Original Author	Original Content on Stackoverflow
Question	user403830	View Question on Stackoverflow
Solution 1 - C#	hunter	View Answer on Stackoverflow

How to include ampersand in connection string?

C# Problem Overview

C# Solutions

Solution 1 - C#

Select method in List<t> Collection

Are email addresses allowed to contain non-alphanumeric characters?

Attributions