You can call `OfType&lt;DataRow&gt;()` on the `DataRowCollection`. 

Assuming you&#39;re using .NET 4.0, which introduces covariance:

    // Presumably your table is of some type deriving from TypedTableBase&lt;T&gt;,
    // where T is an auto-generated type deriving from DataRow.
    IEnumerable&lt;DataRow&gt; collection = myTypedTable;

The [table type itself][1] implements `IEnumerable&lt;T&gt; where T : DataRow`.

Otherwise:

    IEnumerable&lt;DataRow&gt; collection = myTypedTable.Cast&lt;DataRow&gt;();

  [1]: http://msdn.microsoft.com/en-us/library/bb358258.aspx

A simple direct solution is to use the method &quot;Select()&quot; of a System.Data.DataTable object, which produces &quot;DataRow[]&quot;. From this you can treat as an IEnumberable&lt;DataRow&gt; using Linq like below:

    List&lt;MyItem&gt; items = dtItems.Select().Select(row =&gt; new MyItem(row)).ToList();

Providing a useful list of objects for each row.

There is a built in extension method if you include `System.Data.DataSetExtensions.dll` in to your project that adds a `AsEnumerable()` method.

    IEnumerable&lt;DataRow&gt; collection = TypedDataSet.TypedTableBase&lt;DataRow&gt;.AsEnumerable();

I&#39;m getting a compile error at the following method.

    public static boolean isValidPasswd(String passwd) {
        String reg = &quot;^(?=.*[0-9])(?=.*[a-z])(?=.*[A-Z])(?=.*[~#;:?/@&amp;!\&quot;&#39;%*=&#172;.,-])(?=[^\\s]+$).{8,24}$&quot;;
        return Pattern.matches(reg, passwd);
    }

&lt;pre&gt;
at Utility.java:[76,74] unmappable character for 
enoding UTF-8. 74th character is&#39; &quot; &#39;
&lt;/pre&gt;

How can I fix this? Thanks.


&quot;Unmappable character for encoding UTF-8&quot; error

In our application we have a lot of sensitive configuration settings, which we are storing in a xml file which is again encrypted.

This secure file has to be decrypted in runtime and the configuration values read. but an issue arises that the key and initialization vector is hardcoded in the code and hence anyone can read it using Reflector. 

What is the best way to store encryption keys in .NET so no one can read them  using Reflector?

Best way to store encryption keys in .NET C#

I would like to do something like this in .NET 3.5. What&#39;s the quickest way?  

    IEnumerable&lt;DataRow&gt; collection = 
        TypedDataSet.TypedTableBase&lt;DataRow&gt;.Rows as IEnumerable&lt;DataRow&gt;;

Convert DataRowCollection to IEnumerable&lt;T&gt;

I would like to do something like this in .NET 3.5. What's the quickest way?
<pre><code class="hljs language-swift">IEnumerable&#x3C;DataRow> collection = 
 TypedDataSet.TypedTableBase&#x3C;DataRow>.Rows as IEnumerable&#x3C;DataRow>;
</code></pre>

I am interested in how to take musical notes (e.g A, B, C#, etc) or chords (multiple notes at the same time) and write them to a wav file.

From what I understand, each note has a specific frequency associated with it (for perfect pitch) - for example A4 (the A above middle C) is 440 Hz (complete list 2/3 of the way down &lt;a href=&quot;http://www.dolmetsch.com/musictheory1.htm&quot;&gt;This Page&lt;/a&gt;). 

If my understanding is correct, this pitch is in the frequency domain, and so needs the inverse fast fourier transform applying to it to generate the time-domain equivalent?

What I want to know is:

 - How do chords work? Are they the average of the pitches?
 - How is the length of time to play each note specified, when the contents of the wav file is a waveform?
 - how is the result of multiple notes being inverse FFT&#39;d converted to an array of bytes, which make up the data in a wav file?
 - any other relevant information relating to this.

Thanks for any help you can give. If giving code examples, I am using C# and the code I am currently using to create wav files is as follows:

    int channels = 1;
    int bitsPerSample = 8;
    //WaveFile is custom class to create a wav file.
    WaveFile file = new WaveFile(channels, bitsPerSample, 11025);

    int seconds = 60;
    int samples = 11025 * seconds; //Create x seconds of audio

    // Sound Data Size = Number Of Channels * Bits Per Sample * Samples

    byte[] data = new byte[channels * bitsPerSample/8 * samples];

    //Creates a Constant Sound
    for(int i = 0; i &lt; data.Length; i++)
    {
        data[i] = (byte)(256 * Math.Sin(i));
    }
    file.SetData(data, samples);

This creates (somehow) a constant sound - but I don&#39;t understand completely how the code correlates with the result.



Writing musical notes to a wav file

When is it appropriate to use either the `Monitor` class or the `lock` keyword for thread safety in C#?

**EDIT:**
It seems from the answers so far that `lock` is short hand for a series of calls to the `Monitor` class.  What exactly is the lock call short-hand for?  Or more explicitly,

    class LockVsMonitor
    {
        private readonly object LockObject = new object();
        public void DoThreadSafeSomethingWithLock(Action action)
        {
            lock (LockObject)
            {
                action.Invoke();
            }
        }
        public void DoThreadSafeSomethingWithMonitor(Action action)
        {
            // What goes here ?
        }
    }


**Update**

Thank you all for your help :  I have posted a another question as a follow up to some of the information you all provided.  Since you seem to be well versed in this area, I have posted the link: https://stackoverflow.com/questions/4979331/what-is-wrong-with-this-solution-to-locking-and-managing-locked-exceptions

Monitor vs lock

I currently have a WebSocket between JavaScript and a server programmed in C#. In JavaScript, I can pass data easily using an associative array:

    var data = {&#39;test&#39;: &#39;val&#39;,
                &#39;test2&#39;: &#39;val2&#39;};

To represent this data object on the server side, I use a `Dictionary&lt;string, string&gt;`, but this is more &#39;typing-expensive&#39; than in JavaScript:

    Dictionary&lt;string, string&gt; data = new Dictionary&lt;string,string&gt;();
    data.Add(&quot;test&quot;, &quot;val&quot;);
    data.Add(&quot;test2&quot;, &quot;val2&quot;);

Is there some kind of literal notation for associative arrays / `Dictionary`s in C#?

Literal notation for Dictionary in C#?

How do I convert a list to a string in C#?

When I execute `toString` on a List object, I get:

&gt; System.Collections.Generic.List`1[System.String]


Convert a list to a string in C#

In C#, Does foreach automatically call Dispose on any object implementing IDisposable?


http://msdn.microsoft.com/en-us/library/aa664754(v=vs.71).aspx seems to indicate that it does:

*Otherwise, the collection expression is of a type that implements System.IEnumerable, and the expansion of the foreach statement is:
Copy

    IEnumerator enumerator = 
            ((System.Collections.IEnumerable)(collection)).GetEnumerator();
    try {
       while (enumerator.MoveNext()) {
          ElementType element = (ElementType)enumerator.Current;
          statement;
       }
    }
    finally {
       IDisposable disposable = enumerator as System.IDisposable;
       if (disposable != null) disposable.Dispose();
    }

Does foreach automatically call Dispose?

I have tried this:

    public static class ListHelper
    {
        public static string ToString&lt;T&gt;(this IList&lt;String&gt; list)
        {
            return string.Join(&quot;, &quot;, list.ToArray());
        }
    
        public static string ToString&lt;T&gt;(this String[] array)
        {
            return string.Join(&quot;, &quot;, array);
        }
    }

But it does not work, both for `string[]` and `List&lt;string&gt;`. Maybe I need some special annotations?

How to create an extension method for ToString?

Alrighty, I&#39;m taking data from a list that I populate a DataGridView with and am exporting it to a text file. I&#39;ve already done the function to export it to a CSV, and would like to do a plain text version as well.

Because the Titles and other elements are variable in length, when the file is saved and then opened in Notepad it looks like a mess because nothing lines up.

I&#39;d like to have the output look like this:

    Sample Title One   Element One   Whatever Else
    Sample Title 2     Element 2     Whatever Else
    S. T. 3            E3            Whatever Else

I figure that I can loop through each of the elements in order to get the length of the longest one so I can calculate how many spaces to add to each of the remaining element.

My main question is: **Is there an elegant way to add a variable number of chars into a string?** It&#39;d be nice to have something like: `myString.insert(index, charToInsert, howManyToInsert);` 

Of course, I can obviously just write a function to do this via a loop, but I wanted to see if there was a better way of doing it.

Thanks in advance!

-Sootah

C# - Insert a variable number of spaces into a string? (Formatting an output file)

What difference is there between the `WebClient` and the `HttpWebRequest` classes in .NET? They both do very similar things. In fact, why weren&#39;t they merged into one class (too many methods/variables etc may be one reason but there are other classes in .NET which breaks that rule).

Thanks.

What difference is there between WebClient and HTTPWebRequest classes in .NET?

How to create xml document with node prefix like:

    &lt;sphinx:docset&gt;
      &lt;sphinx:schema&gt;
        &lt;sphinx:field name=&quot;subject&quot;/&gt;
        &lt;sphinx:field name=&quot;content&quot;/&gt;
        &lt;sphinx:attr name=&quot;published&quot; type=&quot;timestamp&quot;/&gt;
     &lt;/sphinx:schema&gt;
   &lt;/sphinx:docset&gt;

When I try to run something like `new XElement(&quot;sphinx:docset&quot;)` i getting exception 

&gt; Unhandled Exception: System.Xml.XmlException: The &#39;:&#39; character, hexadecimal val
ue 0x3A, cannot be included in a name.  
   at System.Xml.XmlConvert.VerifyNCName(String name, ExceptionType exceptionTyp
e)  
   at System.Xml.Linq.XName..ctor(XNamespace ns, String localName)  
   at System.Xml.Linq.XNamespace.GetName(String localName)  
   at System.Xml.Linq.XName.Get(String expandedName)

XElement namespaces (How to?)

I have a `List&lt;MyClass&gt; someList`.

    class MyClass
    {
        public int Prop1...
        public int Prop2...
        public int Prop3...
    }


I would like to know how to get a new distinct `List&lt;MyClass&gt; distinctList` from `List&lt;MyClass&gt; someList`, but only comparing it to `Prop2`.





How to get a distinct list from a List of objects?

I have an object that looks something like this:

    public class Student
    {
        public string Name { get; set; } 
        public int Grade { get; set; }
    }

I would like to create the following query: group grades by student name, order each student group by grades, and order groups by max grade in each group.

So it will look like this: 

    A 100
    A 80
    B 80
    B 50
    B 40
    C 70
    C 30

I created the following query:

    StudentsGrades.GroupBy(student =&gt; student.Name)
        .OrderBy(studentGradesGroup =&gt; studentGradesGroup.Max(student =&gt; student.Grade));
But that returns `IEnumerable` `IGrouping`, and I have no way to sort the list inside, unless I do that in another `foreach` query and add the results to a different list using `AddRange`.

Is there a prettier way to do that?



Linq order by, group by and order by each group?

From what I understand from the documentation of SelectMany, one could use it to produce a (flattened) sequence of a 1-many relationship.

I have following classes

      public class Customer
      {
        public int Id { get; set; }
        public string Name { get; set; }
      }
    
      class Order
      {
        public int Id { get; set; }
        public int CustomerId { get; set; }
        public string Description { get; set; }
      }


I then try to use them using the query expression syntax like so

      var customers = new Customer[]
      {
        new Customer() { Id=1, Name =&quot;A&quot;},
        new Customer() { Id=2, Name =&quot;B&quot;},
        new Customer() { Id=3, Name =&quot;C&quot;}
      };
    
      var orders = new Order[]
      {
        new Order { Id=1, CustomerId=1, Description=&quot;Order 1&quot;},
        new Order { Id=2, CustomerId=1, Description=&quot;Order 2&quot;},
        new Order { Id=3, CustomerId=1, Description=&quot;Order 3&quot;},
        new Order { Id=4, CustomerId=1, Description=&quot;Order 4&quot;},
        new Order { Id=5, CustomerId=2, Description=&quot;Order 5&quot;},
        new Order { Id=6, CustomerId=2, Description=&quot;Order 6&quot;},
        new Order { Id=7, CustomerId=3, Description=&quot;Order 7&quot;},
        new Order { Id=8, CustomerId=3, Description=&quot;Order 8&quot;},
        new Order { Id=9, CustomerId=3, Description=&quot;Order 9&quot;}
      };
    
      var customerOrders = from c in customers
                           from o in orders
                           where o.CustomerId == c.Id
                           select new 
                                  { 
                                     CustomerId = c.Id
                                     , OrderDescription = o.Description 
                                  };
    
      foreach (var item in customerOrders)
        Console.WriteLine(item.CustomerId + &quot;: &quot; + item.OrderDescription);


This gives to what I need.

    1: Order 1
    1: Order 2
    1: Order 3
    1: Order 4
    2: Order 5
    2: Order 6
    3: Order 7
    3: Order 8
    3: Order 9

I assume this translates to using the SelectMany method when not using the query expression syntax?

Either ways, I&#39;m trying to wrap my head around using SelectMany. So even if my above query does not translate to SelectMany, given the two classes and mock data, could someone provide me with a linq query that uses SelectMany?


Linq - SelectMany Confusion

I know we can easily do this by a simple loop, but I want to persue this LINQ/Predicate?

    string[] columnNames = dt.Columns.?

    or

    string[] columnNames = from DataColumn dc in dt.Columns select dc.name;

Get all column names of a DataTable into string array using (LINQ/Predicate)

**How do I change the height of a textbox ?**

Neither of the below work:

    this.TextBox1.Size = new System.Drawing.Size(173, 100);

or

    this.TextBox1.Size.Height = 100;

I wanted to be able to change the single line text box height to fit a font size on it without using multi-line if possible.

Change the Textbox height?

I often need to generate lists of numbers. The intervals can have quite a lot of numbers. I have a method like this:

    public static int[] GetNumbers(int start, int end)
    {
        List&lt;int&gt; list = new List&lt;int&gt;();
        for (int i = start; i &lt; end; i++)
            list.Add(i);
        return list.ToArray();
    }

Is there a way to make it simpler, faster?

I am using .NET 3.5

Generating numbers list in C#

I have 2 classes which have some identical properties. 
I stock into a list properties from 1st class, and after that, I want to take some needed properties and put them into a list of 2nd class type.
I&#39;ve made cast sequence through C# and that runs OK, but I must do with LINQ. I tried to do something but without good results. Help me please with suggestions.

1st Class:

       public class ServiceInfo {
        private long _id;
        public long ID {
            get { return this._id; }
            set { _id = value; }
        }
    
        private string _name;
        public string Name {
            get { return this._name; }
            set { _name = value; }
        }
    
        private long _qty;
        public long Quantity {
            get { return this._qty; }
            set { _qty = value; }
        }
    
        private double _amount;
        public double Amount {
            get { return this._amount; }
            set { _amount = value; }
        }
    
        private string _currency;
        public string Currency {
            get { return this._currency; }
            set { _currency = value; }
        }
    
        private DateTime? _date;
        public DateTime? Date {
            get { return this._date; }
            set { _date = value; }
        }
    }

2nd Class: 

    class InvoiceWithEntryInfo {
        private string currencyField;
    
        private long IdField;
        public long IdIWEI {
            get { return this.IdField; }
            set { IdIWEI = value; }
        }
    
        private string nameField;
        public string NameIWEI {
            get { return this.nameField; }
            set { NameIWEI = value; }
        }
    
        private long qtyField;
        public long QuantityIWEI {
            get { return this.qtyField; }
            set { QuantityIWEI = value; }
        }
    
        private double amountField;
        public double AmountIWEI {
            get { return this.amountField; }
            set { AmountIWEI = value; }
        }
        
        private DateTime dateField;
        public DateTime? DateIWEI {
            get { return this.dateField; }
            set { DateIWEI = value; }
        }
    
        public string OwnerIWEI {
            get; set;
        }
    }

C# sample which runs OK:
...

    var sil = new List&lt;ServiceInfo&gt;();
    var iweil = new List&lt;InvoiceWithEntryInfo&gt;();

...

    if (sil != null)
        {
            foreach (ServiceInfo item in sil)
            {
                iweil.Add(new InvoiceWithEntryInfo
                    {
                        IdIWEI = item.ID,
                        AmountIWEI = item.Amount,
                        DateIWEI = item.Date
                    });
            }


LINQ sample which doesn&#39;t run OK:
 
    iweilCOPY = sil.ConvertAll&lt;InvoiceWithEntryInfo&gt;(a =&gt; (InvoiceWithEntryInfo)a);

    iweilCOPY = sil.FindAll(a =&gt; (sil is InvoiceWithEntryInfo)).ConvertAll&lt;InvoiceWithEntryInfo&gt;(a =&gt; (InvoiceWithEntryInfo)a);

Using LINQ to convert List&lt;U&gt; to List&lt;T&gt;

Is there a class existing in .NET Framework 3.5 that would be equivalent to the .NET 4 [Tuple][1]?

I would like to use it in order to return several values from a method, rather than create a `struct`.


  [1]: http://msdn.microsoft.com/en-us/library/system.tuple.aspx

Equivalent of Tuple (.NET 4) for .NET Framework 3.5

I receive this error when I view an application.

&gt;HTTP Error 500.22 - Internal Server Error (An ASP.NET setting has been detected that does not apply in Integrated managed pipeline mode.)

.Net framework 2.0, 3.5 and 4 are installed and I am using SQL 2008. Can anyone tell me what the solution is for this error?

HTTP Error 500.22 - Internal Server Error (An ASP.NET setting has been detected that does not apply in Integrated managed pipeline mode.)

I love `string.IsNullOrEmpty` method. I&#39;d love to have something that would allow the same functionality for IEnumerable. Is there such? Maybe some collection helper class? The reason I am asking is that in `if` statements the code looks cluttered if the patter is `(mylist != null &amp;&amp; mylist.Any())`. It would be much cleaner to have `Foo.IsAny(myList)`. 

This post doesn&#39;t give that answer: https://stackoverflow.com/questions/3779817/ienumerable-is-empty.



How to check if IEnumerable is null or empty?

i have a list of project objects:

    IEnumerable&lt;Project&gt; projects

a **Project** class as a property called **Tags**.  this is a **int[]**

i have a variable called **filteredTags** which is also a **int[]**.  

So lets say my filtered tags variable looks like this:

     int[] filteredTags = new int[]{1, 3};

I want to filter my list (**projects**) to only return projects that have ALL of the tags listed in the filter (in this case at least tag 1 AND tag 3 in the **Tags** property).

I was trying to use **Where**() and **Contains**() but that only seems to work if i am comparing against a single value.  How would i do this to compare a list against another list where i need a match on all the items in the filtered list ??


filtering a list using LINQ

I know it&#39;s possible to cast a list of items from one type to another (given that your object has a public static explicit operator method to do the casting) one at a time as follows:

    List&lt;Y&gt; ListOfY = new List&lt;Y&gt;();
    
    foreach(X x in ListOfX)
        ListOfY.Add((Y)x);

But is it not possible to cast the entire list at one time? For example,

    ListOfY = (List&lt;Y&gt;)ListOfX;

Shorter syntax for casting from a List&lt;X&gt; to a List&lt;Y&gt;?

Can anyone help me with a `Count` extension method for `IEnumerable` (non generic interface).

I know it is not supported in LINQ but how to write it manually?

Calculating Count for IEnumerable (Non Generic)

Is there an equivalent of `IEnumerable.Any(Predicate&lt;T&gt;)` in JavaScript or jQuery?

I am validating a list of items, and want to break early if error is detected. I could do it using `$.each`, but I need to use an external flag to see if the item was actually found:

    var found = false;
    $.each(array, function(i) {
        if (notValid(array[i])) {
            found = true;
        }
        return !found;
    });

What would be a better way? I don&#39;t like using plain `for` with JavaScript arrays because it iterates over all of its members, not just values.

Content Type	Original Author	Original Content on Stackoverflow
Question	Abdu	View Question on Stackoverflow
Solution 1 - C#	wsanville	View Answer on Stackoverflow
Solution 2 - C#	Dan Tao	View Answer on Stackoverflow
Solution 3 - C#	Michael Erickson	View Answer on Stackoverflow
Solution 4 - C#	Scott Chamberlain	View Answer on Stackoverflow

Convert DataRowCollection to IEnumerable<T>

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Solution 3 - C#

Solution 4 - C#

Best way to store encryption keys in .NET C#

"Unmappable character for encoding UTF-8" error

Attributions