C# Tips

How to reverse string

noreply@blogger.com (Unknown) — Fri, 10 Apr 2009 06:49:00 +0000

   26             string originalString = "123456789";
   27             char[] buffer = originalString.ToCharArray();
   28             Array.Reverse(buffer);
   29             string reversedString = new String(buffer);
   30 
   31             Console.WriteLine();
   32             Console.WriteLine("original string: " + originalString);
   33             Console.WriteLine("reversed string: " + reversedString);

How to fill String variable.

noreply@blogger.com (Unknown) — Thu, 09 Apr 2009 23:44:00 +0000

To fill a string variable, sometimes, they use next way: const string breakLine = "----------";

Seems, next way (usage one of string’s constructor) will be better:

string line = new string('-', 10);
Console.WriteLine("new string('-', 10) >" + line);

Console Output:

Sample of attribute usage in c# (csharp).

noreply@blogger.com (Unknown) — Thu, 05 Jun 2008 11:26:00 +0000

To show usage of attribute let’s write method, which pass all fields of a object and if a field has attribute [NonSerialized], then the method will copy value into the field from second object. The method can be used to restore unserialized fields from original object.

Sample:

Class:

[Serializable]
public class FooClass
{
    public int data1;
    [NonSerialized] public int data2;
    public FooClass(int data1, int data2)
    {
        this.data1 = data1;
        this.data2 = data2;
    }
}

Usage:

FooClass destObject = new FooClass(10, 20);
FooClass sourceObject = new FooClass(10, 30);

Debug.Print("destObject.data2: {0}, sourceObject.data2: {1}", destObject.data2, sourceObject.data2);

RestoreUtils.RestoreNonSerialized(destObject, sourceObject);

Debug.Print("destObject.data2: {0}, sourceObject.data2: {1}", destObject.data2, sourceObject.data2);

Output:

We can see, that method RestoreUtils.RestoreNonSerialized restored values of destObject field data2 from sourceObject.

Sources of RestoreUtils.RestoreNonSerialized

using System;
using System.Reflection;
using System.Collections;

namespace ReflectionServices
{
    public class RestoreUtils
    {
        const BindingFlags flags = BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.Public;

        public static void RestoreNonSerialized(object dest, object source)
        {
            if (dest == null || source == null)
                return;

            Type objectType = dest.GetType();
            if (objectType.IsPrimitive | objectType.IsValueType)
                return;

            FieldInfo[] dstFieldsInfo = objectType.GetFields(flags);
            FieldInfo[] srcFieldsInfo = source.GetType().GetFields(flags);

            for (int fieldIndex = 0; fieldIndex < dstFieldsInfo.Length; fieldIndex++)
            {
                FieldInfo fieldInfo = dstFieldsInfo[fieldIndex];
                if (fieldInfo.IsNotSerialized)
                {
                    object newValue = srcFieldsInfo[fieldIndex].GetValue(source);
                    fieldInfo.SetValue(dest, newValue);
                    continue;
                }

                object dstFieldObject = fieldInfo.GetValue(dest);
                object srcFieldObject = srcFieldsInfo[fieldIndex].GetValue(source);
                if (dstFieldObject != null && srcFieldObject != null)
                    RestoreNonSerialized(dstFieldObject, srcFieldObject);
            }

            IEnumerable dstEnumerable = dest as IEnumerable;
            if (dstEnumerable != null)
            {
                IEnumerable srcEnumerable = source as IEnumerable;
                if (srcEnumerable != null)
                {
                    IEnumerator srcEnumerator = srcEnumerable.GetEnumerator();
                    foreach (Object dstItem in dstEnumerable)
                    {
                        bool next = srcEnumerator.MoveNext();
                        if (!next)
                            break;
                        Object srcItem = srcEnumerator.Current;

                        RestoreNonSerialized(dstItem, srcItem);
                    }
                }
            }
        }
    }
}

Reference:

Attributes (C# Programming Guide)

How to serialize c# object to binary data.

noreply@blogger.com (Unknown) — Thu, 05 Jun 2008 11:04:00 +0000

The simplest way to serialize object, that is use class BinaryFormatter.

Sample of serialization to file:

using (FileStream stream = new FileStream(tempFilePath, FileMode.Create))
{
    BinaryFormatter b = new BinaryFormatter();
    b.Serialize(stream, originalData);
}

Sample of deserialization to file:

Data actualData;
using (FileStream stream = new FileStream(tempFilePath, FileMode.Open))
{
    BinaryFormatter b = new BinaryFormatter();
    actualData = (Data)b.Deserialize(stream);
}

where class Data has attribute [Serializable].

See sources on “C# tips samples” project.

Reference:

BinaryFormatter Class

The simplest way to store object to .xml file in c#.

Comparison of 2 standard c# objects.

noreply@blogger.com (Unknown) — Mon, 05 May 2008 04:16:00 +0000

To sort array (or list) of a objects, we need compare 2 objects and define number:

0 - when 2 objects are same;

+1 - when a 1st object more than 2nd;

-1 - when a 1st object less than 2nd.

Samples:

Sign of number:

int x;
Console.WriteLine(Environment.NewLine + "int x");
Console.WriteLine("Math.Sign({0}) = {1}", x = 10, Math.Sign(x));
Console.WriteLine("Math.Sign({0}) = {1}", x = -10, Math.Sign(x));
Console.WriteLine("Math.Sign({0}) = {1}", x = 0, Math.Sign(x));

Compare 2 strings:

string s1;
string s2;
bool ignoreCase;
Console.WriteLine();
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "a", s2 = "b", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "b", s2 = "a", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "a", s2 = "a", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "aa", s2 = "b", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "bb", s2 = "a", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "A", s2 = "b", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\") = {2}", s1 = "B", s2 = "a", String.Compare(s1, s2));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\", {2}) = {3}", s1 = "a", s2 = "A", ignoreCase = false, String.Compare(s1, s2, ignoreCase));
Console.WriteLine("String.Compare(\"{0}\", \"{1}\", {2}) = {3}", s1 = "a", s2 = "A", ignoreCase = true, String.Compare(s1, s2, ignoreCase));

Compare 2 DateTime objects:

DateTime d1;
DateTime d2;
Console.WriteLine();
Console.WriteLine("DateTime.Compare({0}, {1}) = {2}", d1 = new DateTime(2007, 10, 1), d2 = new DateTime(2007, 10, 1), DateTime.Compare(d1, d2));
Console.WriteLine("DateTime.Compare({0}, {1}) = {2}", d1 = new DateTime(2006, 10, 1), d2 = new DateTime(2007, 10, 1), DateTime.Compare(d1, d2));
Console.WriteLine("DateTime.Compare({0}, {1}) = {2}", d1 = new DateTime(2008, 10, 1), d2 = new DateTime(2007, 10, 1), DateTime.Compare(d1, d2));

Console output:

Reference:

Math.Sign Method

String.Compare Method

DateTime.Compare Method

Sorting with help of delegate Comparison.

noreply@blogger.com (Unknown) — Fri, 02 May 2008 07:48:00 +0000

When we use Generic class List(T), we can easy to sort it with help of method Sort and delegate Comparison.

Sample.

Definition of class Data:

internal class Data
{
    internal int id;
    internal string name;
    internal Data(int id, string name)
    {
        this.id = id;
        this.name = name;
    }
}

Initialization of List<Data>:

List<Data> dataList = new List<Data>();
dataList.Add(new Data(4, "London"));
dataList.Add(new Data(2, "Rome"));
dataList.Add(new Data(3, "New York"));
dataList.Add(new Data(5, "Paris"));
dataList.Add(new Data(1, "Jerusalem"));

DataServices.PrintList("by original order:", dataList);

Sorting dataList by field id:

dataList.Sort(delegate(Data data1, Data data2) { return data1.id - data2.id; });
DataServices.PrintList("by id:", dataList);

Sorting dataList by field name:

dataList.Sort(delegate(Data data1, Data data2) { return String.Compare(data1.name, data2.name); });
DataServices.PrintList("by name:", dataList);

Console output:

Reference:

List(T).Sort Method

Comparison(T) Generic Delegate

Using IComparable and IComparer to compare objects

ReferencesManager 1.0.2 : Utility to check .NET assembly references.

noreply@blogger.com (Unknown) — Tue, 29 Apr 2008 04:15:00 +0000

New build of ReferencesManager (v1.0.2) is released.

The build include new command line switch:

-path=<customer path>

which allows to define additional folders to search referenced assemblies. For example:

ReferencesManager.exe Main.dll -path=D:\0;D:\1

Downloading ReferencesManager 1.0.2

Sources can be downloaded from "C# tips samples" project.

References:

Utility to check .NET assembly references

C# checked and unchecked keywords.

noreply@blogger.com (Unknown) — Sun, 27 Apr 2008 19:50:00 +0000

C# arithmetic statements can be executed in checked or unchecked context. "Checked" context checks overflow and raises exception when a arithmetic overflow is detected.

Sample:

short x;
short y;
short z;

x = 10;
y = 20;
z = (short) (x + y);
Debug.Print("\nz = {0}, where x = {1}, y = {2} and z = (short) (x + y);\n", z, x, y);

x = short.MaxValue;
y = short.MaxValue;
z = (short) (x + y);
Debug.Print("z = {0}, where x = {1}, y = {2} and z = (short) (x + y);\n", z, x, y);

x = short.MaxValue;
y = short.MaxValue;
try
{
    z = checked((short) (x + y));
    Debug.Print("z = {0}, where x = {1}, y = {2}\n", z, x, y);
} catch (OverflowException)
{
    Debug.Print("OverflowException ==> where x = {1}, y = {2} and z = checked((short) (x + y));\n", z, x, y);
}

x = short.MaxValue;
y = short.MaxValue;
z = unchecked((short)(x + y));
Debug.Print("z = {0}, where x = {1}, y = {2} and z = unchecked((short)(x + y));\n", z, x, y);

Reference:

checked (C# Reference)

unchecked (C# Reference)

Checked and Unchecked

CSharp (c#) methods String.PadLeft(), String.PadRight().

noreply@blogger.com (Unknown) — Thu, 24 Apr 2008 07:30:00 +0000

When we need to align output of strings we can use method String.PadLeft() or String.PadRight():

Sample:

string[] initialData = new string[] 
    {"one", "two", 
        "three", "four", "five"};

Console.WriteLine("PadLeft sample");
foreach (string item in initialData)
{
    string processedItem = item.PadLeft(10, '.');
    Console.WriteLine("'{0}'", processedItem);
}

Console.WriteLine("PadRight sample");
foreach (string item in initialData)
{
    string processedItem = item.PadRight(10, '.');
    Console.WriteLine("'{0}'", processedItem);
}

Console output:

Reference:

String.PadLeft Method

String.PadRight Method

CSharp (c#) method String.Join().

noreply@blogger.com (Unknown) — Wed, 23 Apr 2008 09:03:00 +0000

When we should create a string, which consists of array of strings with a separator usually we use a iterator (for, foreach).

For example,

string[] stringData = new string[] {"one", "two", "three"};
string outputContent1 = "";
foreach (string item in stringData)
{
    outputContent1 += item + ";";
}
outputContent1 = outputContent1.Remove(outputContent1.Length - 1);
Debug.Print("output #1: {0}", outputContent1);

Now, we can use csharp (c#) method String.Join:

string outputContent2 = String.Join(";", stringData);
Debug.Print("output #2: {0}", outputContent2);

Output window:

Reference:

String.Join Method

Power of Yield, Generics and Array in csharp (C#).

noreply@blogger.com (Unknown) — Wed, 16 Apr 2008 22:53:00 +0000

When it is necessary to process a array in normal order, we can use statement foreach.

But if we want to process the array in reverse order: from last array's element to first (0) element, we have a problem. Sure, we can use loop for (in reverse order) or call method Array.Reverse() and reverse elements of original array. Now we can suggest a additional way to get reverse processing of array with help of generics and yield.

Sample: process (output to console) int and string array in "normal" and "reverse" orders:

static void SampleReverese()
{
   int[] intArray = new int[] {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
   string[] strArray = new string[] { "zero", "one", "two", "three", "four", "five" };
           
   DisplayArray(intArray);
   DisplayArray(Reverse(intArray));
   DisplayArray(Reverse(strArray));
}

We can note, methods DisplayArray() and ReverseArray() can receive array of any elements.
It is implemented with help of c# generics.

Method Display():

static void DisplayArray<T>(IEnumerable<T> displayedArray)
{
   Console.WriteLine();
   foreach (T item in displayedArray)
   {
       Console.Write("{0} ", item);
   }
}

More interesting how to implement method Reverse() without creation of new array or changing original array.
We use statement yield:

static IEnumerable<T> Reverse<T>(T[] originalArray)
{
   for (int i = originalArray.Length - 1; i>=0; i--)
   {
       yield return originalArray[i];
   }
}
Console:

Reference:

yield (C# Reference)

Generics (C# Programming Guide)

Array.Reverse Method (Array)

foreach, in

How to remove leading and trailing characters from string in csharp (c#).

noreply@blogger.com (Unknown) — Wed, 16 Apr 2008 04:20:00 +0000

To remove leading and trailing characters from string in csharp (c#) we can use methods String.Trim(), String.TrimEnd() or String.TrimStart().

Samples:

originalLine = " message with space, ";
actualLine = originalLine.Trim();
DisplayMessage(originalLine, actualLine);

originalLine = " message with space, ";
actualLine = originalLine.TrimEnd();
DisplayMessage(originalLine, actualLine);

originalLine = " message with space, ";
actualLine = originalLine.TrimStart();
DisplayMessage(originalLine, actualLine);

originalLine = " message with space, ";
actualLine = originalLine.Trim(new char[] { ' ', ',' });
DisplayMessage(originalLine, actualLine);

Sometimes interesting to see implementation of C# methods.

So, let's see method String.Trim(Char[]):

// Removes a string of characters from the ends of this string. 
public String Trim(params char[] trimChars) {
    if (null==trimChars || trimChars.Length == 0) { 
        trimChars=WhitespaceChars;
    }
    return TrimHelper(trimChars,TrimBoth);
}

and basic method TrimHelper():

private String TrimHelper(char[] trimChars, int trimType) { 
    //end will point to the first non-trimmed character on the right
    //start will point to the first non-trimmed character on the Left
    int end = this.Length-1;
    int start=0; 

    //Trim specified characters. 
    if (trimType !=TrimTail)  { 
        for (start=0; start < this.Length; start++) {
            int i = 0; 
            char ch = this[start];
            for( i = 0; i < trimChars.Length; i++) {
                if( trimChars[i] == ch) break;
            } 
            if( i == trimChars.Length) { // the character is not white space
                break; 
            } 
        }
    } 

    if (trimType !=TrimHead) {
        for (end= Length -1; end >= start;  end--) {
            int i = 0; 
            char ch = this[end];
            for(i = 0; i < trimChars.Length; i++) { 
                if( trimChars[i] == ch) break; 
            }
            if( i == trimChars.Length) { // the character is not white space 
                break;
            }
        }
    } 

    //Create a new STRINGREF and initialize it from the range determined above. 
    int len = end -start + 1; 
    if (len == this.Length) {
        // Don't allocate a new string is the trimmed string has not changed. 
        return this;
    }
    else {
        if( len == 0) { 
            return String.Empty;
        } 
        return InternalSubString(start, len, false); 
    }
}

References:

String.Trim Method

Split string to array of strings in csharp (c#).

noreply@blogger.com (Unknown) — Tue, 15 Apr 2008 21:39:00 +0000

When we should divide a string to array of strings by a specific delimiters, we can use method String.Splt().

Samples:

string line = "name,id=1234,,description,user=Jon";

string[] lineItems = line.Split(new char[] { ',' });
DisplayOutput(line, lineItems);

lineItems = line.Split(new char[] { ',', '=' });
DisplayOutput(line, lineItems);

lineItems = line.Split(new char[] { ',', '=' }, 2);
DisplayOutput(line, lineItems);

lineItems = line.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);
DisplayOutput(line, lineItems);

lineItems = line.Split(new string[] { ",", "id=", "user="}, StringSplitOptions.RemoveEmptyEntries);
DisplayOutput(line, lineItems);

References:

String.Split Method

Utility to check .NET assembly references

noreply@blogger.com (Unknown) — Tue, 15 Apr 2008 03:51:00 +0000

Sometimes, when a complex project (many source solutions, dlls, references) is built and run, then we receive a problem with references (here we don't speak about signed assemblies). For example, all dlls has a reference to basic .dll, but a specific .dll has a reference to obsolete version of the basic .dll.

Sample:

MainUtils has a reference to Utils1 (v2.0.0.0) and Utils2 (v2.0.0.0), but Utils2 (v2.0.0.0) has a reference to obsolete version of Utils1 (v1.0.0.0). See folders TestData4References in solution csharp-samples.

When a MainUtils will be run, then a error can be shown.

Utility ReferencesManager.exe helps to show all references and output list of all assemblies full names. This information helps to see same assemblies with different versions.

To start the utility it is necessary to type name of initial executable (or .dll) file:

ReferencesManager.exe MainUtils.exe > MainUtils.log

Content of MainUtils.log:

Received log allows to find Utils1 with different versions 1.0.0.0 and 2.0.0.0 and Utils2, which references to Utils1 version 1.0.0.0.

Limitations of version 1.0.1:

The utility finds assemblies in GAC and in folder of initial assembly only.
The utility doesn't find referenced (in c# source project), but actually not used assemblies.
The utility doesn't output list of problematic assemblies.

Downloading ReferencesManager.exe.

References:

Reflector for .NET

Create and Share Flow Charts, Diagrams and More

Mainstream usage of yield (c#).

noreply@blogger.com (Unknown) — Fri, 11 Apr 2008 05:04:00 +0000

Let's review when csharp statement yield can be really useful. When we need process list (for example, display or calculate a parameter) of generated data we can use simple way and create array:

static public int[] PowerByArray(int number, int exponent)
{
   int[] results = new int[exponent];
   int result = 1;
   for (int i = 0; i < exponent; i++)
   {
       result *= number;
       results[i] = result;
   }
   return results;
}

call method PowerByArray:

Trace.Write("powers list (by array): ");
int[] powers = PowerCalculator.PowerByArray(2, 10);
foreach (int value in powers)
{
   Trace.Write(string.Format("{0} ", value));
}
Trace.WriteLine("");

and next result will be shown:

The way is clear, but it requests to create array. Frequently we cannot allow to create a array, because number of elements and/or size of needed memory.

Usage of yield helps us to avoid creation of array:

static public IEnumerable Power(int number, int exponent)
{
   int result = 1;
   for (int i = 0; i < exponent; i++)
   {
       yield return result *= number;
   }
}

Calling method Power

Trace.Write("powers list (by array): ");
int[] powers = PowerCalculator.PowerByArray(2, 10);
foreach (int value in powers)
{
   Trace.Write(string.Format("{0} ", value));
}
Trace.WriteLine("");

generates next output:

Reference:

yield (C# Reference)

simple example of yield (reverse)

Loops and iterators in c# (5 ways)

Statement "yield".

noreply@blogger.com (Unknown) — Thu, 10 Apr 2008 22:11:00 +0000

When we want to use operator foreach, but want to hide details of implementation we can use interface IEnumerable.

Review next sample:

Let's display list of cities:

Cities cities = new Cities();
foreach (string city in cities)
{
    Trace.WriteLine("city: " + city);
}

where class Cities is implemented:

public class Cities
{
    readonly string[] cities = { "London", "Paris", "Rome", "Jerusalem" } ;
    public IEnumerator GetEnumerator()
    {
        return cities.GetEnumerator();
    }
}

Seems enough simple.

Now we need display cities in reverse order

Trace.WriteLine("Reverse order: ");
foreach (string city in cities.Reverese)
{
    Trace.WriteLine("city: " + city);
}

To receive reverse order we can add property Reverse:

public IEnumerable<string> Reverese
{
    get
    {
        for (int i = cities.Length - 1; i >= 0; i--)
        {
            yield return cities[i];
        }
    }
}

Reference:

yield (C# Reference)

Create Elegant Code with Anonymous Methods, Iterators and Partial Classes.

Loops and iterators in c# (5 ways).

noreply@blogger.com (Unknown) — Mon, 07 Apr 2008 20:58:00 +0000

It is suggested to inspect several ways to implement loop in c#.

For example, we need display all days: Sunday .. Saturday with help of loop (or iterators).

Operator For:

static void sample_For_Days()
{
    for (int index = 0; index < DaysNames.DAYS.Length; index++)
    {
        string day = DaysNames.DAYS[index];
        Console.Write(day + " ");
    }
    Console.WriteLine();
}

Operator foreach:

foreach (string day in DaysNames.DAYS)
{
    Console.Write(day + " ");
}
Console.WriteLine();

Method Array.Foreach:

Array.ForEach(DaysNames.DAYS, 
    delegate(string day) { Console.Write(day + " "); });
Console.WriteLine();

Operator ForEach with help of interfaces IEnumerable and IEnumerator

class implementation

public class DaysOfTheWeek_IEnumerator : IEnumerable, IEnumerator
{
    int index;
    public DaysOfTheWeek_IEnumerator()
    {
        Reset();
    }
    #region IEnumerable
    public IEnumerator GetEnumerator()
    {
        return this;
    }
    #endregion

    #region IEnumerator
    public bool MoveNext()
    {
        return (++index < 7);
    }
    public void Reset()
    {
        index = -1;
    }
    public object Current
    {
        get { return DaysNames.DAYS[index]; }
    }
    #endregion
}

usage of foreach

DaysOfTheWeek_IEnumerator week = new DaysOfTheWeek_IEnumerator();

foreach (string day in week)
{
    Console.Write(day + " ");
}
Console.WriteLine();

Operator ForEach with help of interfaces IEnumerable and statement yield:

class implementation:

public class DaysOfTheWeek_yield : IEnumerable
{
    #region IEnumerable
    public IEnumerator GetEnumerator()
    {
        for (int i = 0; i < DaysNames.DAYS.Length; i++)
        {
            yield return DaysNames.DAYS[i];
        }
    }
    #endregion
}

usage of foreach:

DaysOfTheWeek_IEnumerator week = new DaysOfTheWeek_IEnumerator();

foreach (string day in week)
{
    Console.Write(day + " ");
}
Console.WriteLine();

Console output shows, all methods display same results:

Reference:

foreach, in (C# Reference)

Iterators (C# Programming Guide)

yeild (C# Reference)

How to listen file change notification.

noreply@blogger.com (Unknown) — Sun, 06 Apr 2008 20:04:00 +0000

When we want to receive a notifications about file system changes, we can use class FileSystemWatcher.

Code sample:

string testFolder = Path.GetTempPath();
string testFilePath = Path.Combine(testFolder, "test.tst");
File.Delete(testFilePath);

using (FileSystemWatcher watcher = new FileSystemWatcher(testFolder, "*.tst"))
{
    watcher.NotifyFilter = 
        NotifyFilters.LastAccess | NotifyFilters.LastWrite | 
        NotifyFilters.FileName | NotifyFilters.DirectoryName |
        NotifyFilters.CreationTime | NotifyFilters.Attributes |
        NotifyFilters.Size | NotifyFilters.Security;
    watcher.Created += OnFileChanged;
    watcher.Changed += OnFileChanged;
    watcher.Deleted += OnFileChanged;
    watcher.EnableRaisingEvents = true;

    File.WriteAllText(testFilePath, "text");
    File.AppendAllText(testFilePath, "additional text");
    File.Delete(testFilePath);
}

Output window content:

Notes:

Unfortunately, my experience shows, that FilesystemWatcher doesn't work absolutely correct. In many cases, it doesn't catch a file changing.

Reference:

FileSystemWatcher Class

How to create unique temporary file name and folder.

noreply@blogger.com (Unknown) — Thu, 03 Apr 2008 19:24:00 +0000

As we investigated, it is possible to get temporary Windows folder by method Path.GetTempPath and create temporary file by method Path.GetTempFileName().

Unfortunately, these methods cannot help us to create unique temporary folder or temporary file (method Path.GetTempFileName() can generate only 65 536 unique file names at the same time).

It is suggested to generate unique path and name to use a globally unique identifier (GUID) with help of method Guid.NewGuid(). "Such an identifier has a very low probability of being duplicated." by MSDN.

Method, which can generate unique temporary folder:

static string GetUniquePath()
{
    string uniquePath;
    do
    {
        Guid guid = Guid.NewGuid();
        string uniqueSubFolderName = guid.ToString();
        uniquePath = Path.GetTempPath() + uniqueSubFolderName;
    } while (Directory.Exists(uniquePath));
    Directory.CreateDirectory(uniquePath);
    return uniquePath;
}

The method generated and created such paths:

C:\Documents and Settings\name-f\Local Settings\Temp\b0dc9b66-a32c-586c-815b-dfed844df58c

C:\Documents and Settings\name-f\Local Settings\Temp\18a09210-9107-4a19-ab11-a246c36fec54

By the same way, can be generated and created temporary file path.

Important notes:

1. Don't forget to delete created temporary folder and files after usage.

2. Published method GetUniquePath is not protected for multi-threaded usage.

Reference:

Guid Structure

Guid.NewGuid Method

How to redirect Trace output.

noreply@blogger.com (Unknown) — Wed, 02 Apr 2008 21:14:00 +0000

As we know, for tracing we can use method Trace.WriteLine(). But usually, we want to avoid a creating of detailed log file in production mode and to enable the tracing for testing and debugging purposes only by a configuration changing. So, we should find a way to redirect output of Trace.WriteLine() from standard output to a log file and configures the redirection without rebuilding of application.

Let's write next c# code:

Trace.WriteLine("messageTrace");
Trace.WriteLine("messageError", "Error");
Trace.TraceError("traceErrorMessage");

and define .config file:

Thus, we delete "Default" Trace Listener and add our "myListener' of type TextWriterTraceListener with parameter (log file name) c:\myListener.log.

Additionally, attribute "autoflush" is set in True and method Trace.WriteLine() will store input messages to log file immediately.

Content of file myListener.log:

Reference:

How to configure Trace listener

How to receive temporary path and file name (c#).

noreply@blogger.com (Unknown) — Tue, 01 Apr 2008 20:48:00 +0000

To receive standard Windows temporary path we can use c# method Path.GetTempPath().

To receive uniquely temporary file we can use method Path.GetTempFileName(). The method creates a zero-byte in temporary folder and returns a full path of that file. Path of the file is created by format: <temporary folder>\tmp<4 hex symbols>.tmp (for example, <temporary folder>\tmpF1FB.tmp).

Let's investigate how a method GetTempFileName creates a uniquely temp file:

string tempFolder = Path.GetTempPath();
string uniqueTempFileName = Path.GetTempFileName();
string tempFolder_via_Environment = Environment.GetEnvironmentVariable("TEMP");

Debug.WriteLine("tempFolder: " + tempFolder);
Debug.WriteLine("tempFolder_via_Environment: " + tempFolder_via_Environment);
Debug.WriteLine("uniqTempFileName: " + uniqueTempFileName);

for (int i = 0; i < 0xFFFF; i++)
{
    uniqueTempFileName = Path.GetTempFileName();
    Debug.WriteLine("uniqTempFileName: " + uniqueTempFileName);
    Debug.WriteLine(String.Format("File {0} exists: {1}", uniqueTempFileName, File.Exists(uniqueTempFileName)));
}
Output Window:

So, we can see rule, how GetTempFileName builds file name: "tmp" + counter + ".tmp". If a file with next temporary file name exists, then GetTempFileName will generate next temporary file name.

File with name tmp3DBA.tmp was created manually and see result (tmp3D9, tmp3DBB) in Output Window

When all temporary names will be created, that exception IOException will be raised:

Reference:

Path.GetTempPath Method

Path.GetTempFileName Method

Sample of StackTrace usage.

noreply@blogger.com (Unknown) — Sun, 30 Mar 2008 19:53:00 +0000

Sometimes we want to store in log file error (warning or trace) message and stack trace, from where the message is stored. To solve the problem it is suggested to use class StackTrace.

public class StackTraceSampleClass
{
    const string LOG_FILE_NAME = "stackTraceSample.log";
    public void Execute()
    {
        File.Delete(LOG_FILE_NAME);
        F1(-10);
        F2(-10);
    }
    void F1(int arg)
    {
        F(arg);
    }
    void F2(int arg)
    {
        F(arg);
    }
    double F(int arg)
    {
        if (arg < 0)
        {
            StackTrace stackTrace = new StackTrace(true);
            string logContent = String.Format("unexpected value of arg: {0}, stack: {1}", arg, stackTrace);
            File.AppendAllText(LOG_FILE_NAME, logContent);
            return 0;
        }
        return Math.Sqrt(arg);
    }
}
File stackTraceSample.log in Debug mode:

File stackTraceSample.log in Release mode:

Reference:

StackTrace Class

Sample of C# Trace.Fail() method.

noreply@blogger.com (Unknown) — Sun, 30 Mar 2008 19:26:00 +0000

Often we don't check input parameters, because we have a contract and expect valid parameters values. But sometimes, we want to control critical parameters and somehow inform about invalid input parameters.

In this case, we can use method Debug.Fail() or Trace.Fail().

static int CheckArgument(string argument)
{
    if (argument == null)
    {
        Trace.Fail("CheckArgument(): argument cannot be bull", "CheckArgument()");
        return 0;
    }
    return argument.Length;
}
Method CheckArgument doesn't expect to receive null, but if input parameter argument will be null, we call method Trace.Fail() with relevant message. By default, next message will be shown:

The message will be relevant in debug mode, but in production mode, we don't want to show message to user, but want to inform developer about the problem.

So, we want to change behavior of Fail.

First of all, let's implement new class MyTraceListener and override method Fail (actually 2 method Fails):

public class MyTraceListener : DefaultTraceListener
{
    public override void Fail(string message)
    {
        SendNotification(message);
    }
    public override void Fail(string message, string detailMessage)
    {
        SendNotification(message + ", detailMessage: " + detailMessage);
    }

    void SendNotification(string message)
    {
        // here should be implemented sending email
        StackTrace stackTrace = new StackTrace(1, true);
        Trace.WriteLine("MyTraceListener notification: " + message + " in " + stackTrace);
    }
}

Now, we should define the implemented MyTraceListener as single TraceListenerClass:

MyTraceListener listener = new MyTraceListener();
Trace.Listeners.Clear();
Trace.Listeners.Add(listener);

"Output Visual Studio" Window demonstrates possible notification's output:

Reference:

TraceListener.Fail Method

StackTrace Class

Sources can be found in "Code project C# tips samples" in project Debug, method sample_TraceFail().

How to convert simple types (basic operations) in c#.

noreply@blogger.com (Unknown) — Wed, 26 Mar 2008 20:32:00 +0000

To convert one simple type (for example int), to another simple type (for example float or string) it is suggested to use .NET class BitConverter.

C# code sample:

static void Main()
{
    int intData = 0x01020304;
    byte[] bytesData = BitConverter. GetBytes(intData);
    float floatData = BitConverter.ToSingle(bytesData, 0);
    string stringData = BitConverter.ToString(bytesData);
}

Result values (from VS Locals Window):

Reference:

BitConverter Class

The simplest way to store object to .xml file in c#.

noreply@blogger.com (Unknown) — Wed, 26 Mar 2008 06:04:00 +0000

The simplest way to implement xml serialization in c#:

1. Add attribute [Serializable] for all classes.

2. All public fields will be serialized.

3. If you want to store field as xml attribute add attribute [XmlAttribute("")].

[Serializable]
public class SubData
{
    [XmlAttribute("")]
    public int subDataAsAttribute;
    public int subData;
    public int SubProperty { get { return subDataAsAttribute + subData; } }
}
[Serializable]
public class Data
{
    public int publicIntData;
    internal int internalIntData;
    protected int protectedIntData;
    private int privateIntData;
    public SubData subData;
    public Data()
    {
    }
    public Data(int publicIntData)
    {
        this.publicIntData = publicIntData;
    }
}

4. Create objects XmlSerializer and TextWriter and store needed object to xml file:

string xmlFilePath = "data.xml";
XmlSerializer serializer = new XmlSerializer(typeof(Data));
using (TextWriter writer = new StreamWriter(xmlFilePath))
{
    serializer.Serialize(writer, data);
}

5. To read the stored object use XmlSerializer and TextReader:

Data actualData;
using (TextReader reader = new StreamReader(xmlFilePath))
{
    actualData = (Data) serializer.Deserialize(reader);
}
6. See sample of relevant xml file:

Reference:

XmlSerializer Class