Hidden .NET Base Class Library Classes?

Question

What are your favorite lesser-known .NET Base Class Library classes and methods?

Answer 1

I didn't know about System.Net.WebClient until it was posted in an answer to a question of mine.

WebClient client = new WebClient ();
client.DownloadFile("http://stackoverflow.com/", "target.html");
client.UploadFile("http://mysite.com/", "hello.txt");

Answer 2

Buffer.BlockCopy

Also StringReader and StringWriter.

Oops forgot about: Debugger.Break

Answer 3

FormatterServices

Answer 4

System.Text.UTF8Encoding for converting streams.

Answer 5

BaseValidator Makes writing Custom validated controls much easier.

Answer 6

System.Web.UI.WebControls.MailDefinition

"The MailDefinition class can be used by controls to create a MailMessage object from a text file or a string that contains the body of the e-mail message. Use the MailDefinition class to simplify creating predefined e-mail messages to be sent by a control."

Answer 7

For some reason many people don't kow about System.Text.StringBuilder. I couldn't live without it!

Answer 8

This saves a lot of typing on strings:

string.IsNullOrEmpty()

and

string.IsNullOrWhiteSpace()  // .NET 4 only

Also a hidden gem using events; when declaring an event, a nice way to make sure you never need to check if it's null, is by initializing it to an empty anonymous delegate at declaration time:

public event EventHandler MyASimpleEvent = delegate {};

Answer 9

System.Diagnostics.ConditionalAttribute. It makes the compiler ignore methods or classes that should only be active in certain build profiles. EG:

 [Conditional("DEBUG")]
 private void DumpProperties()
 {
     foreach (PropertyInfo prop in this.GetType().GetProperties())
         Console.WriteLine(prop.GetValue(this, null));
 }

Answer 10

Path class. I can't count the times the lack of its usage came up in code-reviews. People tend to go for the string concatenations and sub-stringage instead of using Path.Combine and Path.GetFileNameWithoutExtension, among others.

Answer 11

A cool way to log the name of the current method you're in:

string myMethodName = MethodBase.GetCurrentMethod().Name;


Console.WriteLine(myMethodName);

Answer 12

System.Runtime.InteropServices.Marshal

I hate having to do interop, and particularly PInvoke, but there are all kinds of goodies in Marshal for turning function pointers into delegates, and vice versa, turning Win32 error codes into something a little more helpful (often only a little though), and so on.

Answer 13

System.Security.SecureString - More people should be aware of this if their program accepts passwords or passphrases, or stores credit card numbers in memory. SecureString values are stored encrypted (obfuscated, rather), but most importantly, they are never swapped to disk and can be disposed of immediately when you're done with them.

They're tricky to use because you can only build them one character at a time (to encourage you to build them by capturing keystrokes as the user types their password), and require three lines of code to recover and then wipe their plain text, but when used properly they can make a program more secure by avoiding the virtual-memory vulnerability.

// Make a SecureString
SecureString sPassphrase = new SecureString();
Console.WriteLine("Please enter your passphrase");
ConsoleKeyInfo input = Console.ReadKey(true);
while (input.Key != ConsoleKey.Enter)
{
   sPassphrase.AppendChar(input.KeyChar);
   Console.Write('*');
   input = Console.ReadKey(true);
}
sPassphrase.MakeReadOnly();

// Recover plaintext from a SecureString
// Marshal is in the System.Runtime.InteropServices namespace
try {
   IntPtr ptrPassphrase = Marshal.SecureStringToBSTR(sPassphrase);
   string uPassphrase = Marshal.PtrToStringUni(ptrPassphrase);
   // ... use the string ...
}
catch {
   // error handling
} 
finally {
   Marshal.ZeroFreeBSTR(ptrPassphrase);
}

Edit: At the end of the example the SecureString is converted into a regular managed string, which makes it vulnerable again (be sure to use the try-catch-finally pattern to Zero the string after you're done with it). SecureString's use is in reducing the surface-area of attack by limiting the number of copies the Garbage Collector will make of the value, and reducing the likelihood of being written to the swap file.

The .Net framework is gaining more support for SecureStrings that help eliminate the need to decrypt it. The PasswordBox control in WPF stores its value in a SecureString, System.Diagnostics.ProcessStartInfo's Password property takes a SecureString, and so does the constructor for X509Certificate2. Some third party components are beginning to take it as native currency, too.

Answer 14

Most definitely String.Join(char separator, string[] list) to create "a,b,c" from {"a","b","c"}. This alleviates keeping track of a boolean to check whether the first item is already used.

Answer 15

The BitConverter.ToString method is very useful when working with binary data. I use it for debugging, traces and within unit testing.

It will take a byte array and return a printable string representation - something like "04-08-01-23-45-67-89-AB-CD-EF".

I also use Regex.Split(string, string) for splitting a delimited strings.

It is somewhat similar to String.Split(), but using Regex.Split() is much more intuitive: Regex.Split() result string array only contain the data you need, while String.Split() result also contains the delimiters.

Answer 16

System.Diagnostics namespace contains many "hidden" gems. I have used extensively the DebuggerStepThroughAttribute, I have subclassed many times the TraceListener class and I want to see in more detail the PerformanceCounter.

Answer 17

System.Convert is a lot nicer than people think.

It's a bit more forgiving on what you put in. Use Reflector to see how it converts between different types.

Ints are defaulted to 0 from bad input, bools to false and so on.

It's made int.Parse, bool.Parse and all other .Parse almost obsolete for me. TryParse is still usefull for the most secure parsing.

Answer 18

System.Linq is saving me a lot of time on Visual Studio 2008.

Answer 19

System.Environment is one of my favorites. Especially the Workingset property.

Answer 20

IEnumerable<T> isn't used nearly enough if you ask me.

Answer 21

System.Web.VirtualPathUtility

Provides utility methods for common virtual path operations.

http://msdn.microsoft.com/en-us/library/system.web.virtualpathutility.aspx

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs)

    Dim sb As New StringBuilder()
    Dim pathstring As String = Context.Request.FilePath.ToString()
    sb.Append("Current file path = " & pathstring & "<br />")
    sb.Append("File name = " & VirtualPathUtility.GetFileName(pathstring).ToString() & "<br />")
    sb.Append("File extension = " & VirtualPathUtility.GetExtension(pathstring).ToString() & "<br />")
    sb.Append("Directory = " & VirtualPathUtility.GetDirectory(pathstring).ToString() & "<br />")
    Response.Write(sb.ToString())

    Dim sb2 As New StringBuilder()
    Dim pathstring1 As String = Context.Request.CurrentExecutionFilePath.ToString()
    sb2.Append("Current Executing File Path = " & pathstring1.ToString() & "<br />")
    sb2.Append("Is Absolute = " & VirtualPathUtility.IsAbsolute(pathstring1).ToString() & "<br />")
    sb2.Append("Is AppRelative = " & VirtualPathUtility.IsAppRelative(pathstring1).ToString() & "<br />")
    sb2.Append("Make AppRelative = " & VirtualPathUtility.ToAppRelative(pathstring1).ToString() & "<br />")
    Response.Write(sb2.ToString())

End Sub

Answer 22

This is cool. VisualStyleInformation Class provides a lot of information about the current visual style of the operating system.

System.Diagnostics.Debugger.Break() is used by virtually everyone but is very convenient for debugging .NET services.

NetworkChange.NetworkAvailabilityChanged Event makes it easy to monitor network availability.

Answer 23

If you are drawing custom Windows Forms controls, then the following classes are essential for your OnPaint() method (or Paint event):

using System.Windows.Forms;

• ControlPaint
• TextRenderer
• *Renderer (eg ButtonRenderer, TextBoxRender, etc)

These classes all provide methods that will do most of the drawing work for you and keep your controls looking professional and native.

Answer 24

TextRenderer.MeasureText() is great for figuring out how large to draw your text. So often I see:

// this == something derived from Control
Graphics g = this.CreateGraphics();
Size size = g.MeasureString(this.Text, this.Font).ToSize();
g.Dispose();

When really all you need is:

Size size = TextRenderer.MeasureText(this.Text, this.Font);

The former is how you did it in 1.0 and 1.1; the latter is how you do it in 2.0+. It's much cleaner, doesn't requiring creating an object which must be disposed, and doesn't leave you open to accidentally not disposing of a resource. Plus if you use TextRenderer.DrawText() your text will look better and localize better. This stuff just plain rocks when you're doing custom controls.

Edit: On the I18N/G11N front, here's more info: the shaping engines for international text have been updated quite a bit in the Uniscribe subsystem of the Windows operating system, but not in GDI+ subsystem. So sometimes things looked strange/wrong if your .NET app was using the Graphics based method (AKA, GDI+). However, using the TextRenderer approach (AKA, Uniscribe) eliminates these problems and allows you to render text correctly (perfectly?) in the new locales introduced with Windows XP SP2 (such as Bengali and Croatian). (Caveat emptor: I have no idea how or even if either of these methods play with vendor specific extensions to specific code pages.)

Answer 25

For generating code files I like System.CodeDom.

Answer 26

Here's a little snippet to tell which class/method the call is coming from. Useful in some special situations:

StackFrame frame = new StackFrame(1);
frame.GetMethod().Name; //Gets the current method name

MethodBase method = frame.GetMethod();
method.DeclaringType.Name //Gets the current class name

Answer 27

String.Format(). Allows you to get rid of the wonkiness of "This" + " is" + " my favorite " + " Application";

Answer 28

System.Diagnostics.DebuggerDisplay

When you're debugging, if the class is attributed, visual studio will display the information on mouse-over. It even allows you to put in properties of private fields, etc.

[System.Diagnostics.DebuggerDisplay("MyClass: ID={ID} Name={Name} ChildName={_child.Name}")]

Ref: msdn

Answer 29

I like to use System.Collections.CaseInsensitiveComparer to compare strings.

Answer 30

TypeConverter class

It saved me a lot of time. And it helped Stack Overflow users to solve their problems:

• How do I effectively persist a .NET font object ?
• How to convert from Decimal to T?
• Passing int array as parameter in web user control
• How do I override ToString in C# enums?

Answer 31

public static int Compare(string strA, string strB, bool ignoreCase)

Great to compare two strings with possible difference in letter case.

Answer 32

System.Reflection.Assembly.GetExecutingAssembly.Location

Gets the path (and name) of the current running application.

I have a few related commands at my Blog

Answer 33

I just found:

System.Security.Cryptography.ProtectData

Used to encrypt data for the current user or the local machine.

Answer 34

Using StackFrame to get information about calling method and running class. You can travel the stack and get the methodName, calling calss etc. You can get the stackFrame using

StackFrame frame = new StackFrame(n);

Where n is the layer above the current call And then you can retrive information by using its properties. for example use the following the get the information of the calling method:

MethodBase methodBase = frame.GetMethod();

Answer 35

System.Collections.ObjectModel.ObservableCollection<T>

Represents a dynamic data collection that provides notifications when items get added, removed, or when the whole list is refreshed.

Answer 36

System.Data.Common.DbConnectionStringBuilder

and

System.Data.SqlClient.SqlConnectionStringBuilder

These allow you to build a connection string in a programmatic way without have to remember the specific syntax.

Documentation: DbConnectionStringBuilder on MSDN

Answer 37

HashSet<T>. It is a new class in the .NET Framework 3.5 and is very similar to List<T> only better.

http://blogs.msdn.com/bclteam/archive/2006/11/09/introducing-hashset-t-kim-hamilton.aspx

Answer 38

System.Web.Security.FormsAuthentication
.HashPasswordForStoringInConfigFile(string password, string format)

Does the simple and common task of getting the MD5 or SHA1 hash of a given string. Since almost every system I have ever written stored password hashes instead of encrypted data or the plaintext, this is a godsend to avoid mucking about with the Crypto stuff.

Answer 39

Using System.Environment.NewLine instead of "\r\n".

Answer 40

The DebuggerStepThroughAttribute is great for properties and also for those helper functions that you have no desire to step through. Unfortunately, it seems rarely known:

http://msdn.microsoft.com/en-us/library/system.diagnostics.debuggerstepthroughattribute.aspx

Answer 41

Not really hidden but:

• System.Drawing.Printing.PrinterSettings.InstalledPrinters: Returns a collection with all printer names installed in the machine.

Answer 42

Getting the list of countries. Useful for populating the drop down box.

foreach (CultureInfo ci in CultureInfo.GetCultures(CultureTypes.AllCultures & ~CultureTypes.NeutralCultures
{
       RegionInfo ri = new RegionInfo(ci.LCID);
       Console.WriteLine(ri.EnglishName);
}

ref: http://jdconley.com/blog/archive/2007/09/05/list-of-country-names.aspx#1

Answer 43

Expanding the My Namespace has always been useful to me

Namespace My

    <Global.Microsoft.VisualBasic.HideModuleName()> _
    Friend Module MyStuff
        Sub Foo()

        End Sub
    End Module

End Namespace

Answer 44

I'd have to say System.ComponentModel.BackgroundWorker.

It's not exactly easy to use, because you still have to understand how asynchronous method calls work, and you have to know about avoiding cross-thread exceptions, using Invoke to update the UI, etc. But it's considerably easier to use than System.Threading.Thread, which is what a lot of developers gravitate towards when they need to implement a background process.

Answer 45

Type.TryParse()

Environment.NewLine

Answer 46

System.Configuration.Install.AssemblyInstaller to install services programmatically

Answer 47

More of a runtime feature, but I recently learned that there are two garbage collectors. The workstation gc and the server gc. Workstation is the default, but server is much faster on multicore machines.

<configuration>
   <runtime>
      <gcServer enabled="true"/>
   </runtime>
</configuration>

Be careful. The server gc requires more memory.

Answer 48

System.Runtime.Remoting.Proxies.RealProxy.

This class is pretty esoteric and normally only used in weird remoting scenarios; however, I have used it for the ability to dynamically implement an interface. It is also used by some mocking frameworks for the same purpose. See also Extending RealProxy.

Answer 49

Very helpful class to measure performance System.Diagnostics.StopWatch
See detailed posts here

Answer 50

MatchEvaluator Delegate: Represents the method that is called each time a regular expression match is found during a Replace method operation.

Answer 51

You can play default windows sounds this way :

System.Media.SystemSounds.Beep.Play();
...
System.Media.SystemSounds.Question.Play();

Answer 52

In line with String.IsNullOrEmpty().....

String.Empty

usage:

string s = String.Empty;
//OR
string s = string.Empty;

instead of

string s = "";

Answer 53

WeakReference. Extract from here ...

The garbage collector cannot collect an object in use by an application while the application's code can reach that object. The application is said to have a strong reference to the object.

A weak reference permits the garbage collector to collect the object while still allowing the application to access the object.

This can be used to implement weak events, see here

---

Deep comparison of XmlTrees

XDocument.DeepEquals

Compares the values of two nodes, including the values of all descendant nodes.

Answer 54

Tired of typing the unwieldy

string.Equals(x, y, StringComparison.CurrentCultureIgnoreCase)

?

Instead, try one of the properties on the StringComparer class:

StringComparer Properties

Instead of the above, you can type:

StringComparer.CurrentCultureIgnoreCase.Equals(x, y);

Even though it's only slightly shorter, it's nice because it keeps the focus on the two things you're comparing, without the distraction of the StringComparison.CurrentCultureIgnoreCase parameter. And you can break it up if you like:

var comparer = StringComparer.CurrentCultureIgnoreCase;
comparer.Equals(x, y);

Answer 55

This isn't really a method but just something I found in the String class source:

// The Empty constant holds the empty string value.
// We need to call the String constructor so that the compiler doesn't mark this as a literal.
// Marking this as a literal would mean that it doesn't show up as a field which we can access 
// from native.
public static readonly String Empty = "";

Answer 56

FormatterServices.GetUninitializedObject

Creates a new instance of a type without calling any constructor. This will work with private constructors, non-parameterless-constructors, any type of constructor (since they aint called).

I believe this is the only way to ensure that a static constructor on a type is executed if you only have a Type instance. (You can not invoke it with reflection, and the Activator may fail due to nonmatching constructors.)

A somewhat esoteric problem, and solution.

Answer 57

Ignore Attribute on Unit-Tests for ignoring slow performance tests during development

Answer 58

Decimal preserves trailing zeros :

decimal x = 1.0m;
decimal y = 1.00m;
decimal z = 1m;

Assert.IsTrue(x == y);
Assert.IsFalse(x.ToString() == y.ToString());

Assert.AreEqual("1.0", x.ToString(CultureInfo.InvariantCulture));
Assert.AreEqual("1.00", y.ToString(CultureInfo.InvariantCulture));
Assert.AreEqual("1", z.ToString(CultureInfo.InvariantCulture));

Assert.AreEqual("1.000", (x*y).ToString(CultureInfo.InvariantCulture));

This behavior is documented in the MSDN library.

The decimal.Parse method keeps track of trailing zeros too :

decimal x= decimal.Parse("1.0", CultureInfo.InvariantCulture);
decimal y= decimal.Parse("1.00", CultureInfo.InvariantCulture);

Assert.AreEqual("1.0", x.ToString(CultureInfo.InvariantCulture));
Assert.AreEqual("1.00", y.ToString(CultureInfo.InvariantCulture));

Answer 59

Really useful class is System.Diagnostics.Stopwatch. It saves you from inventing a bicycle every time you need to measure time. It's really helpful when you need to make some time dependent work (perhaps periodic) in some thread.

Answer 60

System.Net.Mail.MailAddress - no more regexp for server-side email address validation ;)

Answer 61

I came across this today System.Data.SqlTypes.SqlDateTime

it has

System.Data.SqlTypes.SqlDateTime.MinValue;
System.Data.SqlTypes.SqlDateTime.MaxValue;

among other methods & properties.

Answer 62

Convert hexadecimal\octal\binary string to decimal:

Convert.ToInt32("2A", 16); // equals 42
Convert.ToInt32("52", 8); // equals 42
Convert.ToInt32("101010", 2); // equals 42

A great way to convert numbers to byte array:

byte[] bytes = BitConverter.GetBytes(32767);

Or better, use Jon Skeet's MiscUtil for endian bit conversion.

Answer 63

Easy way of making an MD5 or SHA1 hash:

string hash = System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile("string to hash", "MD5");

Quick way of generating a unique, temporary file on disk:

string tempFilePath = System.IO.Path.GetTempFileName();

The System.Web.VirtualPathUtility class also has some interesting methods for manipulating file paths.

Parse an enum into a string array in one line (eg. get all known colours from KnowColor enumeration into an array):

string[] colours = System.Enum.GetNames(typeof(System.Drawing.KnownColor));

If you want to annoy your server admin when he's at the console, add this to your web app :D

System.Media.SystemSounds.Exclamation.Play();

Answer 64

System.Security.SecurityElement.Escape

Escapes XML entities from a string so you can use it within an XML element. It's used by the framework in generation WS-Security XML, but saves four string replace statements in your own code.

Answer 65

I use these built-in delegate types (and their "overloaded" cousins) all the time:

• Func<T, TResult>
• Action<T>
• Predicate<T>

Along with Lambdas is C# 3.0 they're pretty useful and can help make things more readable. (You can of course still use them with C# 2.0 and anonymous delegates).

Answer 66

System.IO.Path.Combine

Use this instead of concatenating the 2 strings yourself.

Answer 67

Use the

System.Diagnostics.Stopwatch

Don't do StartTime with DateTime, and then EndTime with DateTime.

See this answer.

Answer 68

I don't think it's a hidden feature, but I don't see it used often:

[System.Diagnostics.DebuggerStepThrough]

Quite useful when you have a pile of accessor-type functions or something which you don't want to be stepping into while debugging.

Answer 69

Here's one, inspired by Marcc's related Diagnostics attribute:

System.Diagnostics.DebuggerDisplay

It allows you to define the format of the string displayed in the Immediate / Locals window of Visual Studio, providing a string like "Person: {name} Cars: {cars.Count}" will display in the windows like "Person: John Doe Cars: 2".

Answer 70

My favorite hidden feature is the SDK. OK, not very hidden, for some people, but most people seem to be able to develop .NET applications only with a tool or IDE, like Visual Studio. The SDK is free, and for small applications it's way quicker for me to write them up in emacs and then just build them with the command line compilers, csc.exe or vbc.exe.

Plus all the SDK tools are handy, too. XML Schema Definition Tool (xsd.exe), Strong Name Tool (sn.exe), and many others.

Answer 71

TypeDescriptor when using Windows Forms data binding. This is how BindingSource can pretend to be any other object type.

Answer 72

I found several cases where people were not aware of certain properties of the Environment class. In particular, I cleaned up several places in code and changed it to:

• Environment.NewLine (unit testing a templating engine that runs in Mono on *nix and .NET on Windows = HUGE improvement)
• Environment.CurrentDirectory (replaced Path.GetFullPath('.') throughout a file-manipulating utility)

Answer 73

String.Empty seems to be a hidden feature for many developers. String.IsNullOrEmpty(string) too.

Answer 74

The Managed, Native, and COM Interop Team at CodePlex have released a modified, open source TlbImp tool that allows simple creation of customized wrappers for pesky COM libraries.

Answer 75

If you have a custom MSBuild task in your project that processes a file and subsequently creates .cs files to include in the same build, changes to the source file of the transformation often won't show in debugging without building twice. When you are generating a single file based solely on the content of a single source file, this task is best solved with a SingleFileGenerator. For multiple inputs and/or outputs, you may be stuck with an MSBuild task. In this case you can fix Visual Studio's dependency analysis by adding the following to your .csproj file:

<PropertyGroup>
  <UseHostCompilerIfAvailable>False</UseHostCompilerIfAvailable>
</PropertyGroup>

It's introduces a few other annoyances, but it will allow you to have deterministic, correct single builds (a rather important goal).

Answer 76

Microsoft.VisualBasic.IsNumeric(object)

Despite being in the Microsoft.VisualBasic.dll assembly, this method can be called by C# just as easily and can quickly let you know if the object being tested can be evaluated as a number.

Related to it are the various TryParse() methods, which attempt to evaluate an object as a number but don't raise exceptions if the call fails... These can be found under a variety of different types such as System.Int32 and System.DateTime

Answer 77

If you're trying to convert between big/little endian then there is IPAddress.HostToNetworkOrder and IPAddress.NetworkToHostOrder. Why these methods were not part of the BitConverter class and in the obvious place people will look we'll never know.

Answer 78

[System.Diagnostics.ConditionalAttribute] - can be used instead of ugly preprocessor directives. For instance:

[Conditional("DEBUG")]
public void Validate()
{
    // ...
}

Answer 79

I have to add Exception.GetBaseException(). I can't know how many times I've this code instead:

while(e.InnerException != null)
    e = e.InnerException;
return e.Message;

instead of just:

return e.GetBaseException().Message;

Answer 80

The Action lambda is a delegate and hence gets the same delegate goodies that regular ones do - such as BeginInvoke():

new Action(() => MethodIWantToRunAsychronously())
  .BeginInvoke(new AsyncCallback(x => ThingToDoWhenMethodReturns()), null);

What it does: Spawns a new thread and runs MethodIWantToRunAsychronously() on it while your continuing to execute the current method on the current thread. When MethodIWantToRunAsychronously completes, ThingToDoWhenMethodReturns() is called (still) on the new thread.

Answer 81

FormatterServices.GetUninitializedObject Activator.CreateInstance

Has someone mentioned above two?

Answer 82

Membership.GeneratePassword() (msdn) will generate a secure temporary password for you.

Answer 83

ToString() method of Object base class is really nice thing. Override it then bring mouse over instance variable in debug time after instance variable created. Don't even need DebuggerDisplay

class Program
{

    string name;
    string surname;
    static void Main(string[] args)
    {
        Program instance = new Program() { name = "James", surname = "hetfield" };
        Console.ReadKey();
    }
    public override string ToString()
    {
        return string.Format("name is {0}, surname is {1}",name,surname);
    }
}

Answer 84

string.Join([seperator], [array])

Couple this with LINQ and it rocks!

string.Join(",", customers.Select(c => c.Name).ToArray());

All your customer names in a CSV with one line of code :-)

Answer 85

System.Xml.XmlConvert contains lots of nice static methods to convert between XSD types and .Net types.