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FileInfo.OpenRead Method

Definition

Namespace:
System.IO
Assemblies:
mscorlib.dll, System.IO.FileSystem.dll
Assemblies:
netstandard.dll, System.Runtime.dll
Assemblies:
netstandard.dll, System.IO.FileSystem.dll
Assemblies:
netstandard.dll, System.IO.FileSystem.dll, System.Runtime.dll
Assembly:
System.IO.FileSystem.dll
Assembly:
mscorlib.dll
Assembly:
netstandard.dll
Source:
FileInfo.cs
Source:
FileInfo.cs
Source:
FileInfo.cs
Source:
FileInfo.cs

Creates a read-only FileStream.

public:
 System::IO::FileStream ^ OpenRead();
public System.IO.FileStream OpenRead();
member this.OpenRead : unit -> System.IO.FileStream
Public Function OpenRead () As FileStream

Returns

FileStream

A new read-only FileStream object.

Exceptions

UnauthorizedAccessException

Name 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.

Examples

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.
//
//
//
//
//
//
//
//
//
//
//
//

Imports System.IO
Imports System.Text

Public Class Test

    Public Shared Sub Main()
        Dim path As String = "c:\temp\MyTest.txt"
        Dim fi As FileInfo = New FileInfo(path)
        Dim fs As FileStream

        ' Delete the file if it exists.
        If fi.Exists = False Then
            'Create the file.
            fs = fi.Create()
            Dim info As Byte() = New UTF8Encoding(True).GetBytes("This is some text in the file.")
            'Add some information to the file.
            fs.Write(info, 0, info.Length)
            fs.Close()
        End If

        'Open the stream and read it back.
        fs = fi.OpenRead()
        Dim b(1023) As Byte
        Dim temp As UTF8Encoding = New UTF8Encoding(True)

        Do While fs.Read(b, 0, b.Length) > 0
            Console.WriteLine(temp.GetString(b))
        Loop
        fs.Close()
    End Sub
End Class
'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.
'
'
'
'
'
'
'
'
'
'
'
'
'

Remarks

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

Applies to

See also