This documentation is archived and is not being maintained.

FileInfo Constructor

Initializes a new instance of the FileInfo class, which acts as a wrapper for a file path.

Namespace:  System.IO
Assembly:  mscorlib (in mscorlib.dll)

public FileInfo(
	string fileName


Type: System.String
The fully qualified name of the new file, or the relative file name. Do not end the path with the directory separator character.


fileName is null.


The caller does not have the required permission.


The file name is empty, contains only white spaces, or contains invalid characters.


Access to fileName is denied.


The specified path, file name, or both exceed the system-defined maximum length. For example, on Windows-based platforms, paths must be less than 248 characters, and file names must be less than 260 characters.


fileName contains a colon (:) in the middle of the string.

You can specify either the fully qualified or the relative file name, but the security check gets the fully qualified name.

The following example uses this constructor to create two files, which are then written to, read from, copied, and deleted.

using System;
using System.IO;

class Test 
    public static void Main() 
        string path = @"c:\temp\MyTest.txt";
        FileInfo fi1 = new FileInfo(path);

        if (!fi1.Exists) 
            //Create a file to write to.
            using (StreamWriter sw = fi1.CreateText()) 

        //Open the file to read from.
        using (StreamReader sr = fi1.OpenText()) 
            string s = "";
            while ((s = sr.ReadLine()) != null) 

            string path2 = path + "temp";
            FileInfo fi2 = new FileInfo(path2);

            //Ensure that the target does not exist.

            //Copy the file.
            Console.WriteLine("{0} was copied to {1}.", path, path2);

            //Delete the newly created file.
            Console.WriteLine("{0} was successfully deleted.", path2);

        catch (Exception e) 
            Console.WriteLine("The process failed: {0}", e.ToString());
//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//c:\MyTest.txt was copied to c:\MyTest.txttemp.
//c:\MyTest.txttemp was successfully deleted.

The following example opens an existing file or creates a file, appends text to the file, and displays the results.

using System;
using System.IO;

public class FileInfoMainTest 
    public static void Main() 
        // Open an existing file, or create a new one.
        FileInfo fi = new FileInfo("temp.txt");
        // Create a writer, ready to add entries to the file.
        StreamWriter sw = fi.AppendText();
        sw.WriteLine("This is a new entry to add to the file");
        sw.WriteLine("This is yet another line to add...");
        // Get the information out of the file and display it.
        StreamReader sr = new StreamReader( fi.OpenRead() );
        while (sr.Peek() != -1)
            Console.WriteLine( sr.ReadLine() );
//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//Add as many lines as you like...
//Add another line to the output...
//This is a new entry to add to the file
//This is yet another line to add...

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.