FileInfo.Open FileInfo.Open FileInfo.Open FileInfo.Open Method

Definition

Opens a file with various read/write and sharing privileges.

Overloads

Open(FileMode) Open(FileMode) Open(FileMode) Open(FileMode)

Opens a file in the specified mode.

Open(FileMode, FileAccess) Open(FileMode, FileAccess) Open(FileMode, FileAccess) Open(FileMode, FileAccess)

Opens a file in the specified mode with read, write, or read/write access.

Open(FileMode, FileAccess, FileShare) Open(FileMode, FileAccess, FileShare) Open(FileMode, FileAccess, FileShare) Open(FileMode, FileAccess, FileShare)

Opens a file in the specified mode with read, write, or read/write access and the specified sharing option.

Open(FileMode) Open(FileMode) Open(FileMode) Open(FileMode)

Opens a file in the specified mode.

public:
 System::IO::FileStream ^ Open(System::IO::FileMode mode);
public System.IO.FileStream Open (System.IO.FileMode mode);
member this.Open : System.IO.FileMode -> System.IO.FileStream
Public Function Open (mode As FileMode) As FileStream

Parameters

mode
FileMode FileMode FileMode FileMode

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

Returns

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

Exceptions

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

The file is already open.

Examples

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

using namespace System;
using namespace System::IO;
using namespace System::Text;

int main()
{
   String^ path = "c:\\MyTest.txt";
   FileInfo^ fi = gcnew FileInfo( path );
   
   // Delete the file if it exists.
   if (  !fi->Exists )
   {
      //Create the file.
      FileStream^ fs = fi->Create();
      try
      {
         array<Byte>^info = (gcnew UTF8Encoding( true ))->GetBytes( "This is some text in the file." );
         
         //Add some information to the file.
         fs->Write( info, 0, info->Length );
      }
      finally
      {
         if ( fs )
            delete (IDisposable^)fs;
      }
   }

   //Open the stream and read it back.
   FileStream^ fs = fi->Open( FileMode::Open );
   try
   {
      array<Byte>^b = gcnew array<Byte>(1024);
      UTF8Encoding^ temp = gcnew UTF8Encoding( true );
      while ( fs->Read( b, 0, b->Length ) > 0 )
      {
         Console::WriteLine( temp->GetString( b ) );
      }
   }
   finally
   {
      if ( fs )
         delete (IDisposable^)fs;
   }
}

//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.
//
//
//
//
//
//
//
//
//
//
//
//
//
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.
//
//
//
//
//
//
//
//
//
//
//
//
Imports System
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.Open(FileMode.Open)
        Dim b(1024) 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.
'
'
'
'
'
'
'
'
'
'
'
'

Security

FileIOPermission
for writing to and reading from files. Associated enumerations: Write and Read

See also

Open(FileMode, FileAccess) Open(FileMode, FileAccess) Open(FileMode, FileAccess) Open(FileMode, FileAccess)

Opens a file in the specified mode with read, write, or read/write access.

public:
 System::IO::FileStream ^ Open(System::IO::FileMode mode, System::IO::FileAccess access);
public System.IO.FileStream Open (System.IO.FileMode mode, System.IO.FileAccess access);
member this.Open : System.IO.FileMode * System.IO.FileAccess -> System.IO.FileStream
Public Function Open (mode As FileMode, access As FileAccess) As FileStream

Parameters

mode
FileMode FileMode FileMode FileMode

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

access
FileAccess FileAccess FileAccess FileAccess

A FileAccess constant specifying whether to open the file with Read, Write, or ReadWrite file access.

Returns

A FileStream object opened in the specified mode and access, and unshared.

Exceptions

The caller does not have the required permission.

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

The file is already open.

path is empty or contains only white spaces.

Examples

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

using namespace System;
using namespace System::IO;
using namespace System::Text;

int main()
{
   String^ path = "c:\\MyTest.txt";
   FileInfo^ fi = gcnew FileInfo( path );
   
   // Delete the file if it exists.
   if (  !fi->Exists )
   {
      
      //Create the file.
      FileStream^ fs = fi->Create();
      try
      {
         array<Byte>^info = (gcnew UTF8Encoding( true ))->GetBytes( "This is some text in the file." );
         
         //Add some information to the file.
         fs->Write( info, 0, info->Length );
      }
      finally
      {
         if ( fs )
            delete (IDisposable^)fs;
      }
   }

   //Open the stream and read it back.
   FileStream^ fs = fi->Open( FileMode::Open, FileAccess::Read );
   try
   {
      array<Byte>^b = gcnew array<Byte>(1024);
      UTF8Encoding^ temp = gcnew UTF8Encoding( true );
      while ( fs->Read( b, 0, b->Length ) > 0 )
      {
         Console::WriteLine( temp->GetString( b ) );
      }
      try
      {
         //Try to write to the file.
         fs->Write( b, 0, b->Length );
      }
      catch ( Exception^ e ) 
      {
         Console::WriteLine( "Writing was disallowed, as expected: {0}", e );
      }
   }
   finally
   {
      if ( fs )
         delete (IDisposable^)fs;
   }
}
//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.
//
//
//
//
//
//
//
//
//
//
//
//
//Writing was disallowed, as expected: System.NotSupportedException: Stream does 
//not support writing.
//   at System.IO.__Error.WriteNotSupported()
//   at System.IO.FileStream.Write(Byte[] array, Int32 offset, Int32 count)
//   at main() in c:\documents and settings\MyComputer\my documents\
//visual studio 2005\projects\finfo open2\finfo open2\
//cpp_console_application.cpp:line 46
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, FileAccess.Read)) 
        {
            byte[] b = new byte[1024];
            UTF8Encoding temp = new UTF8Encoding(true);
            while (fs.Read(b,0,b.Length) > 0) 
            {
                Console.WriteLine(temp.GetString(b));
            }

            try 
            {
                //Try to write to the file.
                fs.Write(b,0,b.Length);
            } 
            catch (Exception e) 
            {
                Console.WriteLine("Writing was disallowed, as expected: {0}",
                    e.ToString());
            }
        }
    }
}
//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.
//
//
//
//
//
//
//
//
//
//
//
//
//Writing was disallowed, as expected: System.NotSupportedException: Stream does 
//not support writing.
//   at System.IO.__Error.WriteNotSupported()
//   at System.IO.FileStream.Write(Byte[] array, Int32 offset, Int32 count)
//   at Test.Main() in C:\Documents and Settings\My Computer\My Documents\
//Visual Studio 2005\Projects\finfo open2\finfo open2\Program.cs:line 39

imports System
imports System.IO
imports System.Text

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

		' Delete the file if it exists.
		If fi.Exists = False
			'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.Open(FileMode.Open, FileAccess.Read)
		Dim b(1024) As byte
		Dim temp As UTF8Encoding = New UTF8Encoding(true)

		Do While fs.Read(b,0,b.Length) > 0
			Console.WriteLine(temp.GetString(b))
		Loop
            Try
                fs.Write(b,0,b.Length)
                Catch e As Exception
                Console.WriteLine("Writing was disallowed, as expected: {0}", e.ToString())
            End Try
        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.
'
'
'
'
'
'
'
'
'
'
'
'
'Writing was disallowed, as expected: System.NotSupportedException: Stream does 
'not support writing.
'   at System.IO.__Error.WriteNotSupported()
'   at System.IO.FileStream.Write(Byte[] array, Int32 offset, Int32 count)
'   at VB_Console_Application.Test.Main() in C:\Documents and Settings\MyComputer
'\My Documents\Visual Studio 2005\Projects\finfo open2\finfo open2\Module1.vb:line 34
'

Security

FileIOPermission
for writing to and reading from files. Associated enumerations: Write and Read

See also

Open(FileMode, FileAccess, FileShare) Open(FileMode, FileAccess, FileShare) Open(FileMode, FileAccess, FileShare) Open(FileMode, FileAccess, FileShare)

Opens a file in the specified mode with read, write, or read/write access and the specified sharing option.

public:
 System::IO::FileStream ^ Open(System::IO::FileMode mode, System::IO::FileAccess access, System::IO::FileShare share);
public System.IO.FileStream Open (System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share);
member this.Open : System.IO.FileMode * System.IO.FileAccess * System.IO.FileShare -> System.IO.FileStream
Public Function Open (mode As FileMode, access As FileAccess, share As FileShare) As FileStream

Parameters

mode
FileMode FileMode FileMode FileMode

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

access
FileAccess FileAccess FileAccess FileAccess

A FileAccess constant specifying whether to open the file with Read, Write, or ReadWrite file access.

share
FileShare FileShare FileShare FileShare

A FileShare constant specifying the type of access other FileStream objects have to this file.

Returns

A FileStream object opened with the specified mode, access, and sharing options.

Exceptions

The caller does not have the required permission.

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

The file is already open.

path is empty or contains only white spaces.

Examples

The following example demonstrates opening a file for reading and writing, but disallowing access to other users or processes.

using namespace System;
using namespace System::IO;
int main()
{
   
   // Open an existing file, or create a new one.
   FileInfo^ fi = gcnew FileInfo( "temp.txt" );
   
   // Open the file just specified such that no one else can use it.
   FileStream^ fs = fi->Open( FileMode::OpenOrCreate, FileAccess::ReadWrite, FileShare::None );
   
   // Create another reference to the same file.
   FileInfo^ nextfi = gcnew FileInfo( "temp.txt" );
   try
   {
      
      // Try opening the same file, which was locked by the previous process.
      nextfi->Open( FileMode::OpenOrCreate, FileAccess::Read );
      Console::WriteLine( "The file was not locked, and was opened by a second process." );
   }
   catch ( IOException^ ) 
   {
      Console::WriteLine( "The file could not be opened because it was locked by another process." );
   }
   catch ( Exception^ e ) 
   {
      Console::WriteLine( e );
   }

   
   // Close the file so it can be deleted.
   fs->Close();
}
//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//
//The file could not be opened because it was locked by another process.
using System;
using System.IO;

public class OpenTest 
{
    public static void Main() 
    {
        // Open an existing file, or create a new one.
        FileInfo fi = new FileInfo("temp.txt");

        // Open the file just specified such that no one else can use it.
        FileStream fs = fi.Open( FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None );

        // Create another reference to the same file.
        FileInfo nextfi = new FileInfo("temp.txt");        

        try 
        {
            // Try opening the same file, which was locked by the previous process.
            nextfi.Open( FileMode.OpenOrCreate, FileAccess.Read );

            Console.WriteLine("The file was not locked, and was opened by a second process.");
        } 
        catch (IOException) 
        {
            Console.WriteLine("The file could not be opened because it was locked by another process.");
        } 
        catch (Exception e) 
        {
            Console.WriteLine(e.ToString());
        }

        // Close the file so it can be deleted.
        fs.Close();
    }
}

//This code produces output similar to the following; 
//results may vary based on the computer/file structure/etc.:
//
//The file could not be opened because it was locked by another process.
Imports System
Imports System.IO

Public Class OpenTest

    Public Shared Sub Main()
        ' Open an existing file, or create a new one.
        Dim fi As New FileInfo("temp.txt")

        ' Open the file just specified such that no one else can use it.
        Dim fs As FileStream = fi.Open(FileMode.OpenOrCreate, FileAccess.ReadWrite, FileShare.None)

        ' Create another reference to the same file.
        Dim nextfi As New FileInfo("temp.txt")

        Try
            ' Try opening the same file, which was locked by the previous process.
            nextfi.Open(FileMode.OpenOrCreate, FileAccess.Read)
            Console.WriteLine("The file was not locked, and was opened by a second process.")
        Catch i as IOException
            Console.WriteLine(i.ToString())
        Catch e As Exception
            Console.WriteLine(e.ToString())
        End Try

        ' Close the file so it can be deleted.
        fs.Close()
    End Sub 'Main
End Class 'OpenTest
'This code produces output similar to the following; 
'results may vary based on the computer/file structure/etc.:
'
'System.IO.IOException: The process cannot access the file 
''C:\Documents and Settings\mydirectory\My Documents\Visual Studio 2005
'\Projects\fileinfoopen\fileinfoopen\obj\Release\temp.txt' 
'because it is being used by another process.
'at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
'at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, 
'Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions
'options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy)
'at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access,
'FileShare share) at System.IO.FileInfo.Open(FileMode mode, FileAccess access)
'at VB_Console_Application.OpenTest.Main() in C:\Documents and Settings
'\mydirectory\My Documents\Visual Studio 2005\Projects\VB_Console_Application
'\VB_Console_Application\Module1.vb:line 19

Security

FileIOPermission
for writing to and reading from files. Associated enumerations: Write and Read

See also

Applies to