eXclusiveMinds » File Handling

Tutorial about loading text from file and assigning it to string.

eXclusiveMinds — Tue, 01 Dec 2009 19:53:58 +0000

This is simple example that demonstrates how can we load text string and assign it to variable of type string. By using method “StreamReader.ReadToEnd” we can load text from given file.
i. Create instance of class StreamReader
ii. Pass filepath as a parameter
iii. Youcan also pass Stream Instance to constructor.
iv. Call ReadToEnd();
v. close stream
UTF-8 is default file encoding for StreamReader.

// Create instance of StreamReader
StreamReader myStreamReader = new StreamReader(myFilePath); 
string text = myStreamReader.ReadToEnd(); 
myStreamReader.Close();

How to get File Attributes in C#

eXclusiveMinds — Sun, 26 Oct 2008 00:29:52 +0000

Following example demonstrates how to get or set file attributes; how to add attributes and how to remove attributes from current ones.

Get file attributes

We can get file attributes by using static method File.GetAttributes. This method returns FileAttributes which is bitwise combination of the file attribute flags.

string myfilePath = @"c:\sample.txt";
FileAttributes attributes = File.GetAttributes(myfilePath);

Set file attributes

We can set file attributes by using static method File.SetAttributes. Parameter of the method is a bitwise combination of FileAttributes enumeration.

File.SetAttributes(myfilePath, FileAttributes.Normal);
File.SetAttributes(myfilePath, FileAttributes.Archive |
                             FileAttributes.ReadOnly);

Example showing how we can check for file attributes
First we can check whether file has any attribute or not and get current attributes then we can apply bitwise AND (&) operator with other attributes.

bool isReadOnly = ((File.GetAttributes(myfilePath) & FileAttributes.ReadOnly) == FileAttributes.ReadOnly);
bool isHidden = ((File.GetAttributes(myfilePath) & FileAttributes.Hidden) == FileAttributes.Hidden);
bool isArchive = ((File.GetAttributes(myfilePath) & FileAttributes.Archive) == FileAttributes.Archive);
bool isSystem = ((File.GetAttributes(myfilePath) & FileAttributes.System) == FileAttributes.System);

Example showing how we can add attributes to file
First we can get current attributes of file then we can use bitwise OR (|) with other attributes.

File.SetAttributes(myfilePath, File.GetAttributes(myfilePath) | FileAttributes.Hidden);
File.SetAttributes(myfilePath, File.GetAttributes(myfilePath) | (FileAttributes.Archive |
                                                             FileAttributes.ReadOnly));

Example showing how we can Clear/Delete file attributes
First we can get current attributes of file then we can use the operator (AND (&)) with a mask.

File.SetAttributes(myfilePath, File.GetAttributes(myfilePath) & ~FileAttributes.Hidden);
File.SetAttributes(myfilePath, File.GetAttributes(myfilePath) & ~(FileAttributes.Archive |
                                                              FileAttributes.ReadOnly));

Get File Time C#

eXclusiveMinds — Mon, 13 Oct 2008 00:26:08 +0000

Following example demonstrate how we can get file time info, it’s creation time, modification time or last access time.

We can get it in two ways:
i. Using File class.
ii. Using FileInfo class.

Example File class (Getting file time)

If we need to get only one specific time we can use File class.

// Getting local time
DateTime creationTimeLocal = File.GetCreationTime(@"D:\sample.txt");
DateTime lastWriteTimeLocal = File.GetLastWriteTime(@"D:\sample.txt");
DateTime lastAccessTimeLocal = File.GetLastAccessTime(@"D:\sample.txt");
 
// Getting UTC time
DateTime fileCreationTimeUtc = File.GetCreationTimeUtc(@"D:\sample.txt");
DateTime fileLastWriteTimeUtc = File.GetLastWriteTimeUtc(@"D:\sample.txt");
DateTime fileLastAccessTimeUtc = File.GetLastAccessTimeUtc(@"D:\sample.txt");

Example FileInfo class (Getting file time)

If we need to get multiple file time we ca use FileInfo class.

FileInfo myFileInfo = new FileInfo(@"D:\sample.txt");
 
// Getting local time
DateTime creationTimeLocal = myFileInfo.CreationTime;
DateTime lastWriteTimeLocal = myFileInfo.LastWriteTime;
DateTime lastAccessTimeLocal = myFileInfo.LastAccessTime;
 
// Getting UTC time
DateTime creationTimeUtc = myFileInfo.CreationTimeUtc;
DateTime lastWriteTimeUtc = myFileInfo.LastWriteTimeUtc;
DateTime lastAccessTimeUtc = myFileInfo.LastAccessTimeUtc;

Get Application Directory in C#

eXclusiveMinds — Sun, 07 Sep 2008 00:32:24 +0000

This example demonstrates how can we get application or assembly folder.

Geting Directory of the windows forms application

To get directory we need to use static property ExecutablePath from Application in System.Windows.Forms namespace.

By using static method GetDirectoryName of Path class we can get only the folder part of the path.

string appPath = Path.GetDirectoryName(Application.ExecutablePath);

Getting Directory of loaded assembly

By using the method Assembly.GetExecutingAssembly we can get assembly of currently executing program.
By using method Assembly.GetAssembly we can get assembly in which the specified class is defined. Finally, we can get a assembly file path using Assembly.CodeBase property.

string appPath = Path.GetDirectoryName(
                     Assembly.GetAssembly(typeof(MyClassName)).CodeBase);

Delete All Files in directory using C#

eXclusiveMinds — Sat, 16 Aug 2008 00:36:37 +0000

Following examples shows how to delete all files from given a folder in C#.

Example

using System.IO;
string[] filePaths = Directory.GetFiles(@"c:\MyDir\");
foreach (string filePath in filePaths)
  File.Delete(filePath);

Example (using anonymous method)

 
Array.ForEach(Directory.GetFiles(@"c:\MyDir\"),
              delegate(string path) { File.Delete(path); });

Get Files from Directory using C#

eXclusiveMinds — Wed, 06 Aug 2008 00:39:03 +0000

We’ve this example which demonstrate how to get list of file names from a directory which includs subdirectories also. We can always filter the list of file by specific extension.

We use static method Directory.GetFiles to get file names from the specified directory. Lets get list of files and subfolders in C:\MyDir:

Get files from directory
Method Directory.GetFiles returns string array with files names (full paths).

 
using System.IO;
 
string[] filePaths = Directory.GetFiles(@"c:\MyDir\");

Get files from directory (with specified extension)
You can specify search pattern. You can use wildcard specifiers in the search pattern, e.g. “.gif” to select files with the extension or “a*” to select files beginning with letter “a”.

 
string[] filePaths = Directory.GetFiles(@"c:\MyDir\", "*.gif");

Get files from directory (including all subdirectories)
If you want to search also in subfolders use parameter SearchOption.AllDirectories.

 
string[] filePaths = Directory.GetFiles(@"c:\MyDir\", "*.gif",
                                         SearchOption.AllDirectories);

How to open file using file stream in C#

eXclusiveMinds — Wed, 02 Jul 2008 00:44:50 +0000

Following example shows how can we open files for writing or reading and how do we load and save file using class FileStream in C#. For this we simply create instance of FileStream class with FileMode and FileAccess enumerations as parameters.

FileStream Usage:

Following code is used when opening the file using FileStream. Always close stream; if we do not close the stream this may take some time to be file again accessible.

 
FileStream fs = new FileStream(@"c:\sample.txt", FileMode.Open);
try
{
  //coading
}
finally
{
  fs.Close();
}

Common Scenarios:

Opening file for write and read both.

FileStream fs = new FileStream(@"D:\sample.txt", FileMode.Open);

Opening file for reading

FileStream fs = new FileStream(@"D:\sample.txt", FileMode.Open, FileAccess.Read);

Opening file for writing.

FileStream fs = new FileStream(@"D:\sample.txt", FileMode.Open, FileAccess.Write);

Opening file for writing and creating new one if it doesn’t exist.

FileStream fs = new FileStream(@"D:\sample.txt", FileMode.Append);

Creating new file for write and read / Overwrite if file already exists

FileStream fs = new FileStream(@"D:\sample.txt", FileMode.Create);

Creating new file for write/read and Throw exception if It’s already exists

FileStream fs = new FileStream(@"D:\sample.txt", FileMode.CreateNew);

How to safely read file stream using C#

eXclusiveMinds — Mon, 30 Jun 2008 00:42:27 +0000

Following example shows how do we safely read the file using FileStream in C#.
By calling FileStream.Read method in a loop we can gurantee whole file is correctly read.

Example showing how can we read file safely using FileStream

i. Create FileStream to open the file for reading.
ii. Call FileStream.Read until all the content from file is read.
ii. Close the file stream.

 public static byte[] ReadingFileSafely(string path)
{
    byte[] myBuffer;
    FileStream myStream = new FileStream(path, FileMode.Open, FileAccess.Read);
    //Start reading file to buffer
    try
    {
        int len = (int)myStream.Length;
        myBuffer = new byte[len];
        int count;
        int total = 0;
        while ((count = myStream.Read(myBuffer, total, len - total)) > 0)
            total += count; 
    }
    finally
    {
        myStream.Close();
    }
    return myBuffer;
}