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FileInfo.Open Method (FileMode)

Opens a file in the specified mode.

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

public FileStream Open (
	FileMode mode
)
public FileStream Open (
	FileMode mode
)
public function Open (
	mode : FileMode
) : FileStream

Parameters

mode

A FileMode constant specifying the mode (for example, Open or Append) in which to open the file.

Return Value

A file opened in the specified mode, with read/write access and unshared.

Exception typeCondition

FileNotFoundException

The file is not found.

UnauthorizedAccessException

The file is read-only or is a directory.

DirectoryNotFoundException

The specified path is invalid, such as being on an unmapped drive.

IOException

The file is already open.

The following table lists examples of other typical or related I/O tasks.

To do this...

See the example in this topic...

Create a text file.

How to: Write Text to a File

Write to a text file.

How to: Write Text to a File

Read from a text file.

How to: Read Text from a File

Append text to a file.

How to: Open and Append to a Log File

File.AppendText

FileInfo.AppendText

Rename or move a file.

File.Move

FileInfo.MoveTo

Copy a file.

File.Copy

FileInfo.CopyTo

Get the size of a file.

FileInfo.Length

Get the attributes of a file.

File.GetAttributes

Set the attributes of a file.

File.SetAttributes

Determine if a file exists.

File.Exists

Read from a binary file.

How to: Read and Write to a Newly Created Data File

Write to a binary file.

How to: Read and Write to a Newly Created Data File

Create a directory.

CreateDirectory

Directory

The following example opens a file, adds some information to the file, and reads the file.

using System;
using System.IO;
using System.Text;

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

        // Delete the file if it exists.
        if (!fi.Exists) 
        {
            //Create the file.
            using (FileStream fs = fi.Create()) 
            {
                Byte[] info = new UTF8Encoding(true).GetBytes("This is some text in the file.");
                //Add some information to the file.
                fs.Write(info, 0, info.Length);
            }
        }

        //Open the stream and read it back.
        using (FileStream fs = fi.Open(FileMode.Open)) 
        {
            byte[] b = new byte[1024];
            UTF8Encoding temp = new UTF8Encoding(true);
            while (fs.Read(b,0,b.Length) > 0) 
            {
                Console.WriteLine(temp.GetString(b));
            }
        }
    }
}

import System.*;
import System.IO.*;
import System.Text.*;

class Test
{
    public static void main(String[] args)
    {
        String path = "c:\\temp\\MyTest.txt";
        FileInfo fi = new FileInfo(path);

        // Delete the file if it exists.
        if (!(fi.get_Exists())) {
            //Create the file.
            FileStream fs = fi.Create();

            try {
                ubyte info[] = (new UTF8Encoding(true)).GetBytes("This is " 
                    + "some text in the file.");

                //Add some information to the file.
                fs.Write(info, 0, info.length);
            }
            finally {
                fs.Dispose();
            }
        }

        //Open the stream and read it back.
        FileStream fs = fi.Open(FileMode.Open);

        try {
            ubyte b[] = new ubyte[1024];
            UTF8Encoding temp = new UTF8Encoding(true);

            while ((fs.Read(b, 0, b.length) > 0)) {
                Console.WriteLine(temp.GetString(b));
            }
        }
      finally {
         fs.Dispose();
      }
    } //main
} //Test

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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