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FileInfo.OpenRead Method

Creates a read-only FileStream.

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

public FileStream OpenRead()

Return Value

Type: System.IO.FileStream
A new read-only FileStream object.

ExceptionCondition
UnauthorizedAccessException

path 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.

This method returns a read-only FileStream object with the FileShare mode set to Read.

For a list of common I/O tasks, see Common I/O Tasks.

The following example opens a file as read-only and reads from it.

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

class Test 
{
	
    public static void Main() 
    {
        string path = @"c:\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.OpenRead()) 
        {
            byte[] b = new byte[1024];
            UTF8Encoding temp = new UTF8Encoding(true);

            while (fs.Read(b,0,b.Length) > 0) 
            {
                Console.WriteLine(temp.GetString(b));
            }
        }
    }
}
//This code produces output similar to the following;  
//results may vary based on the computer/file structure/etc.: 
// 
//This is some text in the file. 
// 
// 
// 
// 
// 
// 
// 
// 
// 
// 
// 
//

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

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

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

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