Category Archives: C# .NET

14 Haz

C# Simple Delegate and Event Example

A delegate is a reference type like the other reference types. But instead of referring to an object, a delegate refers to a method. Following example shows event and delegate usage in C#.

Usage:

            EventDelegateExample e = new EventDelegateExample();
            e.ShowedMessage += new EventDelegateExample.MyCustomEventHandler(delegate(string message) 
                {
                    Console.WriteLine("A new message:" + message);
                });

Example:

    class EventDelegateExample
    {
        public delegate void MyCustomEventHandler(string message);
        public event MyCustomEventHandler ShowedMessage;

        public void ShowNewMsg(string s)
        {
            if (ShowedMessage != null)
                ShowedMessage(s);
        }
    }
14 Haz

C# Multithread Singleton Pattern Example

The singleton pattern is a design pattern that restricts the instantiation of a class to one object. This is important when exactly one object is needed to coordinate actions across the system. Following example allows only a single thread to enter the critical area.

    public sealed class Singleton
    {
        private static volatile Singleton _instance = null;
        private static object _syncRoot = new Object();

        /// 
        /// Constructor must be private.
        /// 
        private Singleton() { }

        public static Singleton Instance
        {
            get
            {
                if (_instance == null)
                {
                    lock (_syncRoot)
                    {
                        if (_instance == null)
                            _instance = new Singleton();
                    }
                }
                return _instance;
            }
        }
    }
13 Haz

C# String Formatting for DateTime

These examples shows how to format DateTime using string.Format method.

            DateTime dateTime = DateTime.Now;

            Console.WriteLine(string.Format("{0:yyyy}", dateTime));                 //2014
            Console.WriteLine(string.Format("{0:MMM dd, yyyy}", dateTime));         //Jun 13, 2014
            Console.WriteLine(string.Format("{0:ddd MM, yyyy}", dateTime));         //Fri 06, 2014
            Console.WriteLine(string.Format("{0:dddd MM, yyyy}", dateTime));        //Friday 06, 2014
            Console.WriteLine(string.Format("{0:MMM ddd dd, yyyy}", dateTime));     //Jun Cum 13, 2014
            Console.WriteLine(string.Format("{0:MMMM dddd dd, yyyy}", dateTime));   //June Cuma 13, 2014

            Console.WriteLine(string.Format("{0:yyyy-MM-dd HH:mm:ss}", dateTime));  //2014-06-13 21:05:05
            Console.WriteLine(string.Format("{0:yyyy-MM-dd HH:mm:ss}", dateTime));  //2014-06-13 21:05:05
            Console.WriteLine(string.Format("{0:MM/dd/yy H:mm:ss zzz}", dateTime)); //06.13.14 21:05:05 +03:00

The following table describes the custom date and time format specifiers.

FORMAT SPECIFIER DESCRIPTION
“d” The day of the month, from 1 through 31.
“dd” The day of the month, from 01 through 31.
“ddd” The abbreviated name of the day of the week.
“dddd” The full name of the day of the week.
“f” The tenths of a second in a date and time value.
“ff” The hundredths of a second in a date and time value.
“fff” The milliseconds in a date and time value.
“ffff” The ten thousandths of a second in a date and time value.
“fffff” The hundred thousandths of a second in a date and time value.
“ffffff” The millionths of a second in a date and time value.
“fffffff” The ten millionths of a second in a date and time value.
“F” If non-zero, the tenths of a second in a date and time value.
“FF” If non-zero, the hundredths of a second in a date and time value.
“FFF” If non-zero, the milliseconds in a date and time value.
“FFFF” If non-zero, the ten thousandths of a second in a date and time value.
“FFFFF” If non-zero, the hundred thousandths of a second in a date and time value.
“FFFFFF” If non-zero, the millionths of a second in a date and time value.
“FFFFFFF” If non-zero, the ten millionths of a second in a date and time value.
“g”, “gg” The period or era.
“h” The hour, using a 12-hour clock from 1 to 12.
“hh” The hour, using a 12-hour clock from 01 to 12.
“H” The hour, using a 24-hour clock from 0 to 23.
“HH” The hour, using a 24-hour clock from 00 to 23.
“K” Time zone information.
“m” The minute, from 0 through 59.
“mm” The minute, from 00 through 59.
“M” The month, from 1 through 12.
“MM” The month, from 01 through 12.
“MMM” The abbreviated name of the month.
“MMMM” The full name of the month.
“s” The second, from 0 through 59.
“ss” The second, from 00 through 59.
“t” The first character of the AM/PM designator.
“tt” The AM/PM designator.
“y” The year, from 0 to 99.
“yy” The year, from 00 to 99.
“yyy” The year, with a minimum of three digits.
“yyyy” The year as a four-digit number.
“yyyyy” The year as a five-digit number.
“z” Hours offset from UTC, with no leading zeros.
“zz” Hours offset from UTC, with a leading zero for a single-digit value.
“zzz” Hours and minutes offset from UTC.
“:” The time separator.
“/” The date separator.
“string”
‘string’		 Literal string delimiter.
% Defines the following character as a custom format specifier.
\ The escape character.
Any other character The character is copied to the result string unchanged.
13 Haz

Set the GDAL_DATA Environment Variable Programmatically in C#

You can set programmatically to the GDAL_DATA environment variable as follow.

Sample code:


string path = @"C:\gdal\";
SetValueNewVariable("GDAL_DATA", path + "\\data");
SetValueNewVariable("GEOTIFF_CSV", path + "\\data");
SetValueNewVariable("GDAL_DRIVER_PATH", path + "\\gdalplugins");

private static void SetValueNewVariable(string var, string value)
{
    if (System.Environment.GetEnvironmentVariable(var) == null)
       System.Environment.SetEnvironmentVariable(var, value);
}
13 Haz

Zip and Unzip Files Programmatically in C#

There are many zip library which used to be popular. I will show you two of them.(7Zip and .NET ZipArchive)
7-Zip is a open source file archiver with a high compression ratio. Most of the source code is under the GNU LGPL license.
For more information:
http://www.7-zip.org/

You can use 7-zip library for zip and unzip to the files as follow:


            //Firstly, you should set 7z.dll path.
            SevenZipExtractor.SetLibraryPath(@"C:\7z.dll");

            //Test Code:
            string[] filePaths = new string[]
            {
                @"C:\Folder1\file1.jpg",
                @"C:\Folder1\file2.txt",
                @"C:\Folder1\file1.png",
            };
            ZipFiles(filePaths, @"C:\zippedFile2.zip");

            ZipFolder(@"C:\Folder1", @"C:\zippedFile1.zip", "password");
            Unzip(@"C:\zippedFile1.zip", @"C:\Folder2", "password");

Sample methods(using 7-Zip):


        public void ZipFiles(string[] filePaths, string outputFilePath, string password = null)
        {
            var tmp = new SevenZipCompressor();
            tmp.ScanOnlyWritable = true;
            tmp.CompressFilesEncrypted(outputFilePath, password, filePaths);
        }

        public void ZipFolder(string folderPath, string outputFilePath, string password = null)
        {
            var tmp = new SevenZipCompressor();
            tmp.ScanOnlyWritable = true;
            tmp.CompressDirectory(folderPath, outputFilePath, password);
        }

        public void Unzip(string zippedFilePath, string outputFolderPath, string password = null)
        {
            SevenZipExtractor tmp = null;
            if (!string.IsNullOrEmpty(password))
                tmp = new SevenZipExtractor(zippedFilePath, password);
            else
                tmp = new SevenZipExtractor(zippedFilePath);

            tmp.ExtractArchive(outputFolderPath);
        }

In .NET framework 4.5, System.IO.Compression namespace get some new classes that allow you to work with zip files programmatically.
Sample code:


            //Zip files
            ZipArchive zip = ZipFile.Open(filePath, ZipArchiveMode.Create);
            foreach (string file in filePaths)
            {
                zip.CreateEntryFromFile(file, Path.GetFileName(file), CompressionLevel.Optimal);
            }
            zip.Dispose();

            //Unzip
            ZipFile.CreateFromDirectory(folderPath, zippedFilePath);
            ZipFile.ExtractToDirectory(zippedFilePath, outputFolderPath);