Working with Files in C#.Net

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The Namespace

System.IO provides all the necessary classes, methods, and properties for manipulating directories and files. Table 1 elaborates the main classes under this namespace.

Class	Purpose/Use
Binary Reader and Writer	Read and write primitive data types
Directory, File, DirectoryInfo, and FileInfo	Create, delete, and move files and directories. Get specific information about the files by making use of the properties defined in these classes.
FileStream	Access the files in a random fashion
MemoryStream	Access data stored in memory
StreamWriter and StreamReader	Read and write textual information
StringReader and StringWriter	Read and write textual Information from a string buffer

Table 1—Classes under System.IO

Creating Files by Using the FileInfo Class

With the FileInfo class, you can create new files, access information about the files, delete, and move files. This class also provides methods for opening, reading from, and writing to a file. Below code shows how to create a text file and access its information like its creation time, full name, and so forth.

FileInfo fi = new FileInfo(@"D:\test1.txt");

FileStream fstr = fi.Create();

Console.WriteLine("Creation Time: {0}",f.CreationTime);

Console.WriteLine("Full Name: {0}",f.FullName);

Console.WriteLine("FileAttributes: {0}",f.Attributes.ToString());

//Way to delete test1.txt file.

Console.WriteLine("Press any key to delete the file");

Console.Read();

fstr.Close();

fi.Delete();

The Open() Method

The FileInfo class defines a method named Open() with which you can create files by applying the values of the FileMode and FileAccess enumerations. The following code snippet describes its usage:

FileInfo f = new FileInfo("c:\myfile.txt");

FileStream s = f.Open(FileMode.OpenorWrite, FileAccess.Read);

You then can read from and write to a file by using the object 's'. In the overloaded Open() method, permission is given only for reading from a file. If you want to write to a file, you have to apply the ReadWrite value of FileAccess enumeration. Tables 4 and 5 describe the values of the FileMode and FileAccess enumerations.

Values	Purpose/Use
Append	Opens the file and adds data. This should be used with the FileAccess Write Enumeration value.
Create	Creates a new file. Overwrites any existing file.
CreateNew	Creates a new file. If the file already exists, IOException is thrown.
Open	Opens an existing file
OpenOrCreate	Opens a new file. If there is no file, it creates a new file.
Truncate	Truncates an existing file

Table 4—FileMode Enumeration values

Values	Purpose/Use
Read	Data can be read (retrieved) from the file
ReadWrite	Data can be added to and retrieved from the file
Write	Data can be added to the file

Table 5—FileAccess Enumeration values

Writing to a Text File by Using the StreamWriter Class

You can easily write texts or other information to a file by using the CreateText() method of the FileInfo class. However, you have to obtain a valid StreamWriter. It's this StreamWriter reference that provides the required functionalities for writing to a file. To illustrate, following code snippet writes a series of texts to the Mytext.txt file.

Example 2:

FileInfo f = new FileInfo("Mytext.txt") 

StreamWriter w = f.CreateText();

w.WriteLine("This is from");

w.WriteLine("Chapter 6");

w.WriteLine("Of C# Module");

w.Write(w.NewLine);

w.WriteLine("Thanks for your time");

w.Close();

Reading from a Text File

You can read from a Text file by using the StreamReader class. For this, you have to specify the file name using the static OpenText() method of the File class. Following code reads the contents that we have written in above code (Example 2):

Console.WriteLine("Reading the contents from the file");

StreamReader s = File.OpenText("Mytext.txt");

string read = null;

while ((read = s.ReadLine()) != null)

{

  Console.WriteLine(read);

}

s.Close();

Thanks and enjoy it…….