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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
)

Parameters

mode
Type: System.IO.FileMode

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

Return Value

Type: System.IO.FileStream
A file opened in the specified mode, with read/write access and unshared.

ExceptionCondition
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 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:\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));
            }
        }
    }
}
//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. 
// 
// 
// 
// 
// 
// 
// 
// 
// 
// 
// 
//

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

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