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How do I send out simple debug messages to help with my debugging?

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Recent Posts Visual Studio offers tons of useful debugging features and allows you to step through your code line-by-line. However, there are times when you How do I send out don’t want to step through your application, but want to make it output simple debug simple text strings with variable values, etc. messages to help with Enter the System.Diagnostics.Debug class andmy its debugging? Write* methods. By How do similarly I calculatetoathe way the using the Debug class, you can output messages hash from a Win32 API function OutputDebugString.MD5 However, the beauty of the Debug string? class is that when you build your application using the default Release Howare do generated I play configuration in Visual Studio, no code lines for your default Windowspenalty for using Debug.Write* class. This means there’s no performance sounds? the Debug class in release code. How can I easily log message to a file To use the Debug class, simply add the “ausing System.Diagnostics; ” for debugging statement to your C# code file, and call Debug.Write: purposes? Debug.Write("Hello, Debugger!"); How can I speed up hashtable lookups In addition to Write, you have the possibility call object WriteIf, with to struct as WriteLine and WriteLineIf. For example: keys? bool @this = true; Tags bool that = false; Debug.WriteLineIf(@this || that, "A conditional Hello!");

When you are debugging your application under the Visual Studio .NET Framework debugger, all the messages that are sent out your Write C# by Language 2.0 method calls end up in the Output window (View / OutputC# menu command Language andor Ctrl+W,O on the keyboard). However, if you are running your application outside the Compiler debugger (say, by starting it from Windows Explorer), you can still view C#/VB.NET the messages using tools like DebugViewEquivalents from Sysinternals. Debugger/Debugging Remember, if you build your applicationGeneral using the default Release configuration, even DebugView won’t show IDE your messages because the Debug.Write* calls are eliminated altogether. Tips You can also control code generation by defining the DEBUG conditional directive. Archives Tip: The .NET debugging/tracing architecture also allows you to redirect debugging messages to different destinations, such as text files. See the help October 2006 (2) topic “Trace Listeners” for more information. March 2006 (3) February 2005 (1) [author: Jani Järvinen, C# MVP] December 2004 (4) 2004 (1) | 1 Comments Posted Monday, October 09, 2006 11:19 November AM by CSharpFAQ October 2004 (15) Filed under: Debugger/Debugging August 2004 (3) July 2004 (3) How do I calculate a MD5 June 2004 (1) hash from a string? May 2004 (8) April 2004 (4) March 2004 (36) It is a common practice to store passwords in databases using a hash. MD5 (defined in RFC 1321) is a common hash algorithm, and using it from C# is easy. Here’s an implementation of a method that converts a string to an MD5 hash, which is a 32-character string of hexadecimal numbers. public string CalculateMD5Hash(string input) { // step 1, calculate MD5 hash from input MD5 md5 = System.Security.Cryptography.MD5.Create(); byte[] inputBytes = System.Text.Encoding.ASCII.GetBytes(input); byte[] hash = md5.ComputeHash(inputBytes);

// step 2, convert byte array to hex string StringBuilder sb = new StringBuilder(); for (int i = 0; i < hash.Length; i++) { sb.Append(hash[i].ToString("X2")); } return sb.ToString(); }

An example call: string hash = CalculateMD5Hash("abcdefghijklmnopqrstuvwxyz");

…returns a string like this: C3FCD3D76192E4007DFB496CCA67E13B

To make the hex string use lower-case letters instead of upper-case, replace the single line inside the for loop with this line: sb.Append(hash[i].ToString("x2"));

The difference is the ToString method parameter. [author: Jani Järvinen, C# MVP] Posted Monday, October 09, 2006 11:15 AM by CSharpFAQ | 3 Comments Filed under: .NET Framework How do I play default Windows sounds? Sometimes, you might want to make your application a bit more audible. If you are using .NET 2.0, you can utilize the new System.Media namespace and its SystemSound and SystemSounds classes. The SystemSounds class contains five static properties that you can use to retrieve instances of the SystemSound class. This class in turn contains the Play() method, which you can use to play the wave file associated with the sound in Windows Control Panel. Note that the user can also disable all sounds altogether, which would mean that no sound can be heard through the computer speakers. To play for example the classical beep sound, you could use the following code: System.Media.SystemSounds.Beep.Play();

Similarly, you could play the “Question” sound with this code: System.Media.SystemSounds.Question.Play();

The System.Media namespace is defined in System.dll, so there are no new DLLs you would need to add to your project’s references to use the above code. [author: Jani Järvinen, C# MVP] Posted Monday, March 27, 2006 7:03 PM by CSharpFAQ | 1 Comments Filed under: .NET Framework How can I easily log a message to a file for debugging purposes? Often, you need a way to monitor your applications once they are running on the server or even at the customer site -- away from your Visual Studio debugger. In those situations, it is often helpful to have a simple routine that you can use to log messages to a text file for later analysis. Here’s a simple routine that has helped me a lot for example when writing server applications without an user interface: using System.IO;

public string GetTempPath() { string path = System.Environment.GetEnvironmentVariable("TEMP"); if (!path.EndsWith("\\")) path += "\\"; return path; } public void LogMessageToFile(string msg) { System.IO.StreamWriter sw = System.IO.File.AppendText( GetTempPath() + "My Log File.txt"); try { string logLine = System.String.Format( "{0:G}: {1}.", System.DateTime.Now, msg); sw.WriteLine(logLine); } finally { sw.Close(); } }

With this simple method, all you need to do is to pass in a string like this: LogMessageToFile("Hello, World");

The current date and time are automatically inserted to the log file along with your message. [author: Jani Järvinen, C# MVP] Posted Monday, March 27, 2006 6:59 PM by CSharpFAQ | 6 Comments Filed under: Debugger/Debugging How can I speed up hashtable lookups with struct object as keys? When you have struct objects as the key in a hashtable, the lookup operation of the hashtable performs miserably. This can be attributes to the GetHashCode() function which is used internally to do the lookup. If a struct contains only simple value types (int, short, etc.), the algorithm which computes the GetHashCode creates hashes which fall into mostly the same bucket. Example, lets say, the hashtable creates 10 buckets. Then, most probably, all the keys are being put into the same bucket. Hence when a lookup is performed, the .NET runtime has to traverse through this entire bucket to get the value. BUCKET1 BUCKET2 BUCKET3 BUCKET4 BUCKET5 BUCKET6 BUCKET7 BUCKET8 BUCKET9 BUCKET10-

Value1, Value2, Value3,...,valuen (empty) (empty) (empty) (empty) (empty) (empty) (empty) (empty) (empty)

Hence, instead of the lookup operation being O(1), it becomes O(n) on an average case. To overcome this drawback, consider overriding the GetHashCode() function and making the life easier for the .NET Runtime. An example would be to create a string by merging all your value types in the struct and joining them by using a special character as a demarcator. Since your struct is a lookup criteria, it is sure that all the struct values will be different, and hence the string generated is guaranteed unique. Now the string generated has a method(GetHashCode()), since it is derived from System.Object (like all other objects). Just return the output of this API. A code example will help to understand better. struct { int a; short b; public struct(int _a, short _b) { a = _a; b = _b;

} public override int GetHashCode() { string hash = a.ToString() + ":" b.ToString(); return hash.GetHashCode(); } }

Since you are generating hashcode explicitly which is guaranteed to be unique, it will boost the performance of your lookup. Reference: http://msdn.microsoft.com/library/default.asp?url=/library/enus/cpref/html/frlrfsystemobjectclassgethashcodetopic.asp [author: Vipul Patel, C# MVP] Posted Monday, March 20, 2006 6:54 PM by CSharpFAQ | 18 Comments Where can I find design and coding guidelines for .NET? tipu_77 asked "What are microsoft suggested naming conventions in C#?"

The .NET Framework Team collects their recommendations at their GotDotNet community site. which points to a fairly comprehensive MSDN page Design Guidelines for Class Library Developers. which includes the section Naming Guidelines [Author: SantoshZ] Posted Monday, February 21, 2005 1:30 PM by CSharpFAQ | 4 Comments Filed under: C# Language and Compiler, .NET Framework What does the /target: command line option do in the C# compiler? All the /target: options except module create .NET assemblies. Depending on the option, the compiler adds metadata for the operating system to use when loading the portable executable (PE) file and for the runtime to use in executing the contained assembly or module.

module creates a module.

The metadata in the PE does not include a manifest. Module/s + manifest make an assembly - the smallest unit of deployment. Without the

metadata in the manifest, there is little the runtime can do with a module.

library creates an

assembly without an entry point, by setting the EntryPointToken of the PE's CLR header to 0. If you look at the IL, it does not contain the .entrypoint clause. The runtime cannot start an application if the assembly does not have an entry point.

exe creates an assembly

with an entry point, but sets the Subsystem field of the PE header to 3 (Image runs in the Windows character subsystem - see the _IMAGE_OPTIONAL_HEADER structure in winnt.h). If you ILDASM the PE, you will see this as .subsystem

0x0003. The OS launches this as a console app.

winexe sets the Subsystem field to 2.

(Image runs in the Windows GUI subsystem). The OS launches this as a GUI app. [Author: SantoshZ] See also: Chapter 3 of Inside Microsoft .NET IL assembler (Serge Lidin, Microsoft Press) Metadata and the PE File Structure at MSDN An In-Depth Look into the Win32 Portable Executable File Format - Part 1 and Part 2 (Matt Pietrek, MSDN Magazine) Posted Saturday, December 04, 2004 11:33 PM by CSharpFAQ | 3 Comments Filed under: C# Language and Compiler What is the difference between const and static readonly? The difference is that the value of a static readonly field is set at run time, and can thus be modified by the containing class, whereas the value of a const field is set to a compile time constant. In the static readonly case, the containing class is allowed to modify it only in the variable declaration (through a variable initializer) in the static constructor (instance constructors, if it's not static)

static readonly is typically used if the type of the field is not allowed in a const declaration, or when the value is not known at compile time. Instance readonly fields are also allowed. Remember that for reference types, in both cases (static and instance) the readonly modifier only prevents you from assigning a new reference to the field. It specifically does not make immutable the object pointed to by the reference. class Program { public static readonly Test test = new Test(); static void Main(string[] args) { test.Name = "Program"; test = new Test(); // Error: A static readonly field cannot be assigned to (except in a static constructor or a variable initializer) } } class Test { public string Name; } On the other hand, if Test were a value type, then assignment to test.Name would be an error.

Posted Friday, December 03, 2004 5:13 PM by CSharpFAQ | 3 Comments Filed under: C# Language and Compiler How do I create a constant that is an array? Strictly speaking you can't, since const can only be applied to a field or local whose value is known at compile time. In both the lines below, the right-hand is not a constant expression (not in C#). const int // error const int // error //

[] constIntArray = newint [] {2, 3, 4}; CS0133: The expression being assigned to 'constIntArray' must be constant [] constIntArrayAnother = {2, 3, 4}; CS0623: Array initializers can only be used in a variable or field initializer. Try using a new expression instead.

However, there are some workarounds, depending on what it is you want to achieve. If want a proper .NET array (System.Array) that cannot be reassigned, then static readonly will do for you. static readonly int [] constIntArray = new int[] {1, 2, 3};

The constIntArray field will be initialized before it its first use. If, on the other hand, you really need a const set of values (say as an argument to an attribute constructor), then - if you can limit yourself to integral types - an enum would serve you well. For example: [Flags] public enum Role { Administrator = 1, BackupOperator = 2, // etc. } public class RoleAttribute : Attribute { public RoleAttribute() { CreateRole = DefaultRole; } public RoleAttribute(Role role) { CreateRole = role; } public Role CreateRole { get { return this.createRole; } set { this.createRole = value; } } private Role createRole = 0; public const Role DefaultRole = Role.Administrator | Role.BackupOperator; } [RoleAttribute(RoleAttribute.DefaultRole)] public class DatabaseAccount { //.............. }

RoleAttribute, instead of taking an array, would only take a single argument of flags (appropriately or-ed). If the underlying type of the Role enum is long or ulong, that gives you 64 different Roles. [Author: SantoshZ] Posted Friday, December 03, 2004 9:33 AM by CSharpFAQ | 5 Comments Filed under: C# Language and Compiler, General, Tips How do I get and set Environment variables?

Use the System.Environment class. Specifically the GetEnvironmentVariable and SetEnvironmentVariable methods. Admitedly, this is not a question specific to C#, but it is one I have seen enough C# programmers ask, and the ability to set environment variables is new to the Whidbey release, as is the EnvironmentVariableTarget enumeration which lets you separately specify process, machine, and user.

Brad Abrams blogged on this way back at the start of this year, and followed up with a solution for pre-Whidbey users. [Author: SantoshZ] Posted Thursday, December 02, 2004 9:01 AM by CSharpFAQ | 6 Comments Filed under: General, .NET Framework, Tips Is it possible to output the command-line used to build a project in Visual Studio? Now that Whidbey has been out in Beta for more than a few months, it seems worth revisiting some frequently asked questions which have different (better?) answers now. In Everett (v7.1) the answer used to be No. However, in Whidbey (v8.0), the answer is Yes (and No). For the yes part of the answer, after building, go to the Output Window, select "Show Output from: Build", and about half way down you will see a section like this: Target "Compile" in project "ConsoleApplication1.csproj" Task "Csc" Csc.exe /noconfig /warn:4 /define:DEBUG;TRACE /debug+ /optimize/out:obj\Debug\ConsoleApplication1.exe /reference:C:\WINDOWS\Microsoft.NET\Framework\v2.0.31125\System.Data.dll, C:\WINDOWS.0\Microsoft.NET\Framework\v2.0.31125\System.XML.dll, C:\WINDOWS\Microsoft.NET\Framework\v2.0.31125\System.dll /target:exe /win32icon:App.ico AssemblyInfo.cs Class1.cs The task is invoking the IDE's in-process compiler to perform the equivalent of the above command-line.

Now for the no part of the answer. The project system does not actually execute this command line as part of the build process. As the output says, the IDE directly calls its own in-process compiler to perform the equivalent. However, in all cases, you should get the same results using the command line suggested in the output window. If you don't, you could be looking at a bug. Note: before you cut and paste the build output to the command line, remember to add the path to CSC.EXE [Author: SantoshZ] Posted Tuesday, November 30, 2004 2:54 PM by CSharpFAQ | 6 Comments Filed under: IDE, General, C# Language 2.0 Preprocess Win32 Messages through Windows Forms In the unmanaged world, it was quite common to intercept Win32 messages as they were plucked off the message queue. In that rare case in which you wish to do so from a managed Windows Forms application, your first step is to build a helper class which implements the IMessageFilter interface. The sole method, PreFilterMessage(), allows you to get at the underlying message ID, as well as the raw WPARAM and LPARAM data. By way of a simple example: public class MyMessageFilter : IMessageFilter { public bool PreFilterMessage(ref Message m) { // Intercept the left mouse button down message. if (m.Msg == 513) { MessageBox.Show("WM_LBUTTONDOWN is: " + m.Msg); return true; } return false; } }

At this point you must register your helper class with the Application type: public class mainForm : System.Windows.Forms.Form {

private MyMessageFilter msgFliter = new MyMessageFilter(); public mainForm() { // Register message filter. Application.AddMessageFilter(msgFliter); } … }

At this point, your custom filter will be automatically consulted before the message makes its way to the registered event hander. Removing the filter can be accomplished using the (aptly named) static Application.RemoveMessageFilter() method. Tip from Andrew Troelsen Posted by: Duncan Mackenzie, MSDN This post applies to Visual C# .NET 2002/2003 Posted Wednesday, October 20, 2004 4:59 PM by CSharpFAQ | 7 Comments Filed under: Tips Be Mindful of the References / 'using' / Manifest Relationship Given that the .NET platform encourages binary reuse of types, it is commonplace to set references to external assemblies using the Visual Studio .NET Add Reference dialog box. Many programmers (especially those of the C(++) ilk) fear that adding unnecessary external references can result in a bit of 'code bloat'. Nothing could be further from the truth. When you add assembly references or make use of the 'using' keyword, csc.exe will ignore any assembly which you have not actually made use of in your code. Thus, if you were to set a reference to System.Data.dll and System.Windows.Forms.dll but only authored the following code: using System; using System.Data; // Ignored. using System.Windows.Forms; // Ignored. public class MyClass { public static void Main() { Console.WriteLine("Hi there."); } }

the compiler would only reference the mandatory mscorlib.dll. As you may be aware, when you open up a .NET assembly using ildasm.exe, the MANIFEST icon may be double clicked to open a window describing the binary under investigation. At the very top, you will see a list of each external assembly the current assembly was compiled against (provided that it was actually used): .assembly extern mscorlib { … }

Bottom line? Don't waist your time stripping out unused 'using' statements or assembly references from your application. The C# compiler will do so for you automatically. Tip from Andrew Troelsen Posted by: Duncan Mackenzie, MSDN This post applies to Visual C# .NET 2002/2003/2005 Posted Wednesday, October 20, 2004 4:58 PM by CSharpFAQ | 8 Comments Filed under: Tips Activate 'Full Screen Mode' During your Source Code

Editing Okay, I admit this is a rather lame tip which can hardly qualify as 'insightful', however this is one of my favorite features of Visual Studio .NET (as well as previous editions of the Visual Studio product line) which many folks are (surprisingly) unaware of. Under the View menu you will find a menu item named 'Full Screen'. When activated, the only window displayed will be the active document. This is especially helpful for those working on low resolution monitors, given that the size of your code window can shrink dramatically if you have too many windows docked within the IDE. To escape from full screen, just click the Full Screen button floating over your code window. Tip from Andrew Troelsen Posted by: Duncan Mackenzie, MSDN This post applies to Visual C# .NET 2002/2003/2005 Posted Wednesday, October 20, 2004 4:50 PM by CSharpFAQ | 8 Comments Filed under: Tips Leverage the C# Preprocessor Like other languages in the C-family, C# supports a set of 'preprocessor' directives, most notably #define, #if and #endif (technically, csc.exe does not literally have a preprocessor as these symbols are resolved at the lexical analysis phase, but no need to split hairs…). The #define directive allows you to set up custom symbols which control code compilation. Be very aware that unlike C(++), C#'s #define does not allow you to create macro-like code. Once a symbol is defined, the #if and #endif maybe used to test for said symbol. By way of a common example: #define DEBUG using System; public class MyClass { public static void Main() { #if DEBUG Console.WriteLine("DEBUG symbol is defined!"); #endif } }

When you use the #define directive, the symbol is only realized within the defining file. However if you wish to define project wide symbols, simply access your project's property page and navigate to the "Configuration Properties | Build" node and edit the "Conditional Compilation Constants" edit field. Finally, if you wish to disable a constant for a given file, you may make use of the #undef symbol. Tip from Andrew Troelsen Posted by: Duncan Mackenzie, MSDN This post applies to Visual C# .NET 2002/2003/2005 Posted Wednesday, October 20, 2004 1:20 PM by CSharpFAQ | 6

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