FileStream FileStream FileStream FileStream Constructors

Definition

Overloads

FileStream(SafeFileHandle, FileAccess) FileStream(SafeFileHandle, FileAccess) FileStream(SafeFileHandle, FileAccess) FileStream(SafeFileHandle, FileAccess)

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission.

FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions, FileSecurity) FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions, FileSecurity) FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions, FileSecurity)

Initializes a new instance of the FileStream class with the specified path, creation mode, access rights and sharing permission, the buffer size, additional file options, access control and audit security.

FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions)

Initializes a new instance of the FileStream class with the specified path, creation mode, access rights and sharing permission, the buffer size, and additional file options.

FileStream(String, FileMode, FileAccess, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileAccess, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileAccess, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileAccess, FileShare, Int32, FileOptions)

Initializes a new instance of the FileStream class with the specified path, creation mode, read/write and sharing permission, the access other FileStreams can have to the same file, the buffer size, and additional file options.

FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean) FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean) FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean) FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean)

Initializes a new instance of the FileStream class with the specified path, creation mode, read/write and sharing permission, buffer size, and synchronous or asynchronous state.

FileStream(IntPtr, FileAccess, Boolean, Int32, Boolean) FileStream(IntPtr, FileAccess, Boolean, Int32, Boolean) FileStream(IntPtr, FileAccess, Boolean, Int32, Boolean) FileStream(IntPtr, FileAccess, Boolean, Int32, Boolean)

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission, FileStream instance ownership, buffer size, and synchronous or asynchronous state.

FileStream(String, FileMode, FileAccess, FileShare) FileStream(String, FileMode, FileAccess, FileShare) FileStream(String, FileMode, FileAccess, FileShare) FileStream(String, FileMode, FileAccess, FileShare)

Initializes a new instance of the FileStream class with the specified path, creation mode, read/write permission, and sharing permission.

FileStream(String, FileMode, FileAccess, FileShare, Int32) FileStream(String, FileMode, FileAccess, FileShare, Int32) FileStream(String, FileMode, FileAccess, FileShare, Int32) FileStream(String, FileMode, FileAccess, FileShare, Int32)

Initializes a new instance of the FileStream class with the specified path, creation mode, read/write and sharing permission, and buffer size.

FileStream(SafeFileHandle, FileAccess, Int32, Boolean) FileStream(SafeFileHandle, FileAccess, Int32, Boolean) FileStream(SafeFileHandle, FileAccess, Int32, Boolean) FileStream(SafeFileHandle, FileAccess, Int32, Boolean)

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission, buffer size, and synchronous or asynchronous state.

FileStream(String, FileMode, FileAccess) FileStream(String, FileMode, FileAccess) FileStream(String, FileMode, FileAccess) FileStream(String, FileMode, FileAccess)

Initializes a new instance of the FileStream class with the specified path, creation mode, and read/write permission.

FileStream(IntPtr, FileAccess, Boolean) FileStream(IntPtr, FileAccess, Boolean) FileStream(IntPtr, FileAccess, Boolean) FileStream(IntPtr, FileAccess, Boolean)

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission and FileStream instance ownership.

FileStream(SafeFileHandle, FileAccess, Int32) FileStream(SafeFileHandle, FileAccess, Int32) FileStream(SafeFileHandle, FileAccess, Int32) FileStream(SafeFileHandle, FileAccess, Int32)

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission, and buffer size.

FileStream(String, FileMode) FileStream(String, FileMode) FileStream(String, FileMode) FileStream(String, FileMode)

Initializes a new instance of the FileStream class with the specified path and creation mode.

FileStream(IntPtr, FileAccess) FileStream(IntPtr, FileAccess) FileStream(IntPtr, FileAccess) FileStream(IntPtr, FileAccess)

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission.

FileStream(IntPtr, FileAccess, Boolean, Int32) FileStream(IntPtr, FileAccess, Boolean, Int32) FileStream(IntPtr, FileAccess, Boolean, Int32) FileStream(IntPtr, FileAccess, Boolean, Int32)

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission, FileStream instance ownership, and buffer size.

FileStream(SafeFileHandle, FileAccess) FileStream(SafeFileHandle, FileAccess) FileStream(SafeFileHandle, FileAccess) FileStream(SafeFileHandle, FileAccess)

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission.

public:
 FileStream(Microsoft::Win32::SafeHandles::SafeFileHandle ^ handle, System::IO::FileAccess access);
public FileStream (Microsoft.Win32.SafeHandles.SafeFileHandle handle, System.IO.FileAccess access);
new System.IO.FileStream : Microsoft.Win32.SafeHandles.SafeFileHandle * System.IO.FileAccess -> System.IO.FileStream
Public Sub New (handle As SafeFileHandle, access As FileAccess)

Parameters

handle
SafeFileHandle SafeFileHandle SafeFileHandle SafeFileHandle

A file handle for the file that the current FileStream object will encapsulate.

access
FileAccess FileAccess FileAccess FileAccess

A constant that sets the CanRead and CanWrite properties of the FileStream object.

Exceptions

The caller does not have the required permission.

An I/O error, such as a disk error, occurred.

-or-

The stream has been closed.

The access requested is not permitted by the operating system for the specified file handle, such as when access is Write or ReadWrite and the file handle is set for read-only access.

Remarks

When Close is called, the handle is also closed and the file's handle count is decremented.

FileStream assumes that it has exclusive control over the handle. Reading, writing, or seeking while a FileStream is also holding a handle could result in data corruption. For data safety, call Flush before using the handle, and avoid calling any methods other than Close after you are done using the handle.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

FileShare.Read is the default for those FileStream constructors without a FileShare parameter.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions, FileSecurity) FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions, FileSecurity) FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions, FileSecurity)

Initializes a new instance of the FileStream class with the specified path, creation mode, access rights and sharing permission, the buffer size, additional file options, access control and audit security.

public:
 FileStream(System::String ^ path, System::IO::FileMode mode, System::Security::AccessControl::FileSystemRights rights, System::IO::FileShare share, int bufferSize, System::IO::FileOptions options, System::Security::AccessControl::FileSecurity ^ fileSecurity);
public FileStream (string path, System.IO.FileMode mode, System.Security.AccessControl.FileSystemRights rights, System.IO.FileShare share, int bufferSize, System.IO.FileOptions options, System.Security.AccessControl.FileSecurity fileSecurity);
new System.IO.FileStream : string * System.IO.FileMode * System.Security.AccessControl.FileSystemRights * System.IO.FileShare * int * System.IO.FileOptions * System.Security.AccessControl.FileSecurity -> System.IO.FileStream

Parameters

path
String String String String

A relative or absolute path for the file that the current FileStream object will encapsulate.

mode
FileMode FileMode FileMode FileMode

A constant that determines how to open or create the file.

rights
FileSystemRights FileSystemRights FileSystemRights FileSystemRights

A constant that determines the access rights to use when creating access and audit rules for the file.

share
FileShare FileShare FileShare FileShare

A constant that determines how the file will be shared by processes.

bufferSize
Int32 Int32 Int32 Int32

A positive Int32 value greater than 0 indicating the buffer size. The default buffer size is 4096.

options
FileOptions FileOptions FileOptions FileOptions

A constant that specifies additional file options.

fileSecurity
FileSecurity FileSecurity FileSecurity FileSecurity

A constant that determines the access control and audit security for the file.

Exceptions

path is an empty string (""), contains only white space, or contains one or more invalid characters.

-or-

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in an NTFS environment.

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in a non-NTFS environment.

bufferSize is negative or zero.

-or-

mode, access, or share contain an invalid value.

The file cannot be found, such as when mode is FileMode.Truncate or FileMode.Open, and the file specified by path does not exist. The file must already exist in these modes.

An I/O error, such as specifying FileMode.CreateNew when the file specified by path already exists, occurred.

-or-

The stream has been closed.

The caller does not have the required permission.

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

The access requested is not permitted by the operating system for the specified path, such as when access is Write or ReadWrite and the file or directory is set for read-only access.

-or-

Encrypted is specified for options, but file encryption is not supported on the current platform.

The specified path, file name, or both exceed the system-defined maximum length.

Examples

The following example writes data to a file and then reads the data using the FileStream object.

using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::Security::AccessControl;
using namespace System::Security::Principal;

int main()
{
    try
    {
        // Create a file and write data to it.

        // Create an array of bytes.
        array<Byte>^ messageByte =
            Encoding::ASCII->GetBytes("Here is some data.");

        // Specify an access control list (ACL)
        FileSecurity^ fs = gcnew FileSecurity();

        fs->AddAccessRule(
            gcnew FileSystemAccessRule("MYDOMAIN\\MyAccount",
            FileSystemRights::Modify, AccessControlType::Allow));

        // Create a file using the FileStream class.
        FileStream^ fWrite = gcnew FileStream("test.txt",
            FileMode::Create, FileSystemRights::Modify,
            FileShare::None, 8, FileOptions::None, fs);

        // Write the number of bytes to the file.
        fWrite->WriteByte((Byte)messageByte->Length);

        // Write the bytes to the file.
        fWrite->Write(messageByte, 0, messageByte->Length);

        // Close the stream.
        fWrite->Close();

        // Open a file and read the number of bytes.

        FileStream^ fRead = 
            gcnew FileStream("test.txt", FileMode::Open);

        // The first byte is the string length.
        int length = (int)fRead->ReadByte();

        // Create a new byte array for the data.
        array<Byte>^ readBytes = gcnew array<Byte>(length);

        // Read the data from the file.
        fRead->Read(readBytes, 0, readBytes->Length);

        // Close the stream.
        fRead->Close();

        // Display the data.
        Console::WriteLine(Encoding::ASCII->GetString(readBytes));

        Console::WriteLine("Done writing and reading data.");
    }

    catch (IdentityNotMappedException^)
    {
        Console::WriteLine("You need to use your own credentials " +
            " 'MYDOMAIN\\MyAccount'.");
    }

    catch (IOException^ ex)
    {
        Console::WriteLine(ex->Message);
    }
}

using System;
using System.IO;
using System.Text;
using System.Security.AccessControl;

namespace FileSystemExample
{
    class FileStreamExample
    {
        public static void Main()
        {
            try
            {
                // Create a file and write data to it.

                // Create an array of bytes.
                byte[] messageByte = Encoding.ASCII.GetBytes("Here is some data.");

                // Specify an access control list (ACL)
                FileSecurity fs = new FileSecurity();

                fs.AddAccessRule(new FileSystemAccessRule(@"DOMAINNAME\AccountName",
                                                            FileSystemRights.ReadData,
                                                            AccessControlType.Allow));

                // Create a file using the FileStream class.
                FileStream fWrite = new FileStream("test.txt", FileMode.Create, FileSystemRights.Modify, FileShare.None, 8, FileOptions.None, fs);

                // Write the number of bytes to the file.
                fWrite.WriteByte((byte)messageByte.Length);

                // Write the bytes to the file.
                fWrite.Write(messageByte, 0, messageByte.Length);

                // Close the stream.
                fWrite.Close();

                
                // Open a file and read the number of bytes.

                FileStream fRead = new FileStream("test.txt", FileMode.Open);

                // The first byte is the string length.
                int length = (int)fRead.ReadByte();

                // Create a new byte array for the data.
                byte[] readBytes = new byte[length];

                // Read the data from the file.
                fRead.Read(readBytes, 0, readBytes.Length);

                // Close the stream.
                fRead.Close();

                // Display the data.
                Console.WriteLine(Encoding.ASCII.GetString(readBytes));

                Console.WriteLine("Done writing and reading data.");
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
            }

            Console.ReadLine();
        }
    }
}

Imports System
Imports System.IO
Imports System.Text
Imports System.Security.AccessControl



Module FileStreamExample

    Sub Main()
        Try
            ' Create a file and write data to it.
            ' Create an array of bytes.
            Dim messageByte As Byte() = Encoding.ASCII.GetBytes("Here is some data.")

            ' Specify an access control list (ACL)
            Dim fs As New FileSecurity()

            fs.AddAccessRule(New FileSystemAccessRule("DOMAINNAME\AccountName", FileSystemRights.ReadData, AccessControlType.Allow))

            ' Create a file using the FileStream class.
            Dim fWrite As New FileStream("test.txt", FileMode.Create, FileSystemRights.Modify, FileShare.None, 8, FileOptions.None, fs)

            ' Write the number of bytes to the file.
            fWrite.WriteByte(System.Convert.ToByte(messageByte.Length))

            ' Write the bytes to the file.
            fWrite.Write(messageByte, 0, messageByte.Length)

            ' Close the stream.
            fWrite.Close()


            ' Open a file and read the number of bytes.
            Dim fRead As New FileStream("test.txt", FileMode.Open)

            ' The first byte is the string length.
            Dim length As Integer = Fix(fRead.ReadByte())

            ' Create a new byte array for the data.
            Dim readBytes(length) As Byte

            ' Read the data from the file.
            fRead.Read(readBytes, 0, readBytes.Length)

            ' Close the stream.
            fRead.Close()

            ' Display the data.
            Console.WriteLine(Encoding.ASCII.GetString(readBytes))

            Console.WriteLine("Done writing and reading data.")
        Catch e As Exception
            Console.WriteLine(e)
        End Try

        Console.ReadLine()

    End Sub
End Module

Remarks

The .NET Framework does not support direct access to physical disks through paths that are device names, such as "\\.\PHYSICALDRIVE0 ".

Use this FileStream constructor to apply access rights at the point of creation of a file. To access or modify rights on an existing file, consider using the GetAccessControl and SetAccessControl methods.

The fileOptions parameter is used to provide access to more advanced operations that can be leveraged when creating a FileStream object.

The path parameter can be a file name, including a file on a Universal Naming Convention (UNC) share.

Note

path is not required to be a file stored on disk; it can be any part of a system that supports access through streams. For example, depending on the system, this class can access a physical device.

CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the CanSeek property on the resulting FileStream is false. For additional information, see CanSeek.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileSystemRights, FileShare, Int32, FileOptions)

Initializes a new instance of the FileStream class with the specified path, creation mode, access rights and sharing permission, the buffer size, and additional file options.

public:
 FileStream(System::String ^ path, System::IO::FileMode mode, System::Security::AccessControl::FileSystemRights rights, System::IO::FileShare share, int bufferSize, System::IO::FileOptions options);
public FileStream (string path, System.IO.FileMode mode, System.Security.AccessControl.FileSystemRights rights, System.IO.FileShare share, int bufferSize, System.IO.FileOptions options);
new System.IO.FileStream : string * System.IO.FileMode * System.Security.AccessControl.FileSystemRights * System.IO.FileShare * int * System.IO.FileOptions -> System.IO.FileStream
Public Sub New (path As String, mode As FileMode, rights As FileSystemRights, share As FileShare, bufferSize As Integer, options As FileOptions)

Parameters

path
String String String String

A relative or absolute path for the file that the current FileStream object will encapsulate.

mode
FileMode FileMode FileMode FileMode

A constant that determines how to open or create the file.

rights
FileSystemRights FileSystemRights FileSystemRights FileSystemRights

A constant that determines the access rights to use when creating access and audit rules for the file.

share
FileShare FileShare FileShare FileShare

A constant that determines how the file will be shared by processes.

bufferSize
Int32 Int32 Int32 Int32

A positive Int32 value greater than 0 indicating the buffer size. The default buffer size is 4096.

options
FileOptions FileOptions FileOptions FileOptions

A constant that specifies additional file options.

Exceptions

path is an empty string (""), contains only white space, or contains one or more invalid characters.

-or-

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in an NTFS environment.

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in a non-NTFS environment.

bufferSize is negative or zero.

-or-

mode, access, or share contain an invalid value.

The file cannot be found, such as when mode is FileMode.Truncate or FileMode.Open, and the file specified by path does not exist. The file must already exist in these modes.

An I/O error, such as specifying FileMode.CreateNew when the file specified by path already exists, occurred.

-or-

The stream has been closed.

The caller does not have the required permission.

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

The access requested is not permitted by the operating system for the specified path, such as when access is Write or ReadWrite and the file or directory is set for read-only access.

-or-

Encrypted is specified for options, but file encryption is not supported on the current platform.

The specified path, file name, or both exceed the system-defined maximum length.

Remarks

The .NET Framework does not support direct access to physical disks through paths that are device names, such as "\\.\PHYSICALDRIVE0 ".

Use this FileStream constructor to apply access rights at the point of creation of a file. To access or modify rights on an existing file, consider using the GetAccessControl and SetAccessControl methods.

The fileOptions parameter is used to provide access to more advanced operations that can be leveraged when creating a FileStream object.

The path parameter can be a file name, including a file on a Universal Naming Convention (UNC) share.

Note

path is not required to be a file stored on disk; it can be any part of a system that supports access through streams. For example, depending on the system, this class can access a physical device.

CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the CanSeek property on the resulting FileStream is false. For additional information, see CanSeek.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(String, FileMode, FileAccess, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileAccess, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileAccess, FileShare, Int32, FileOptions) FileStream(String, FileMode, FileAccess, FileShare, Int32, FileOptions)

Initializes a new instance of the FileStream class with the specified path, creation mode, read/write and sharing permission, the access other FileStreams can have to the same file, the buffer size, and additional file options.

public:
 FileStream(System::String ^ path, System::IO::FileMode mode, System::IO::FileAccess access, System::IO::FileShare share, int bufferSize, System::IO::FileOptions options);
public FileStream (string path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share, int bufferSize, System.IO.FileOptions options);
new System.IO.FileStream : string * System.IO.FileMode * System.IO.FileAccess * System.IO.FileShare * int * System.IO.FileOptions -> System.IO.FileStream
Public Sub New (path As String, mode As FileMode, access As FileAccess, share As FileShare, bufferSize As Integer, options As FileOptions)

Parameters

path
String String String String

A relative or absolute path for the file that the current FileStream object will encapsulate.

mode
FileMode FileMode FileMode FileMode

A constant that determines how to open or create the file.

access
FileAccess FileAccess FileAccess FileAccess

A constant that determines how the file can be accessed by the FileStream object. This also determines the values returned by the CanRead and CanWrite properties of the FileStream object. CanSeek is true if path specifies a disk file.

share
FileShare FileShare FileShare FileShare

A constant that determines how the file will be shared by processes.

bufferSize
Int32 Int32 Int32 Int32

A positive Int32 value greater than 0 indicating the buffer size. The default buffer size is 4096.

options
FileOptions FileOptions FileOptions FileOptions

A value that specifies additional file options.

Exceptions

path is an empty string (""), contains only white space, or contains one or more invalid characters.

-or-

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in an NTFS environment.

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in a non-NTFS environment.

bufferSize is negative or zero.

-or-

mode, access, or share contain an invalid value.

The file cannot be found, such as when mode is FileMode.Truncate or FileMode.Open, and the file specified by path does not exist. The file must already exist in these modes.

An I/O error, such as specifying FileMode.CreateNew when the file specified by path already exists, occurred.

-or-

The stream has been closed.

The caller does not have the required permission.

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

The access requested is not permitted by the operating system for the specified path, such as when access is Write or ReadWrite and the file or directory is set for read-only access.

-or-

Encrypted is specified for options, but file encryption is not supported on the current platform.

The specified path, file name, or both exceed the system-defined maximum length.

Examples

The following example writes data to a file and then reads the data using the FileStream object.

#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Text;
using namespace System::Security::AccessControl;

int main()
{
    try
    {
        // Create a file and write data to it.

        // Create an array of bytes.
        array<Byte>^ messageByte =
            Encoding::ASCII->GetBytes("Here is some data.");

        // Create a file using the FileStream class.
        FileStream^ fWrite = gcnew FileStream("test.txt", FileMode::Create,
            FileAccess::ReadWrite, FileShare::None, 8, FileOptions::None);

        // Write the number of bytes to the file.
        fWrite->WriteByte((Byte)messageByte->Length);

        // Write the bytes to the file.
        fWrite->Write(messageByte, 0, messageByte->Length);

        // Close the stream.
        fWrite->Close();


        // Open a file and read the number of bytes.

        FileStream^ fRead = gcnew FileStream("test.txt", 
            FileMode::Open);

        // The first byte is the string length.
        int length = (int)fRead->ReadByte();

        // Create a new byte array for the data.
        array<Byte>^ readBytes = gcnew array<Byte>(length);

        // Read the data from the file.
        fRead->Read(readBytes, 0, readBytes->Length);

        // Close the stream.
        fRead->Close();

        // Display the data.
        Console::WriteLine(Encoding::ASCII->GetString(readBytes));

        Console::WriteLine("Done writing and reading data.");
    }
    catch (IOException^ ex)
    {
        Console::WriteLine(ex->Message);
    }
}
using System;
using System.IO;
using System.Text;
using System.Security.AccessControl;

namespace FileSystemExample
{
    class FileStreamExample
    {
        public static void Main()
        {
            try
            {
                // Create a file and write data to it.

                // Create an array of bytes.
                byte[] messageByte = Encoding.ASCII.GetBytes("Here is some data.");

                // Create a file using the FileStream class.
                FileStream fWrite = new FileStream("test.txt", FileMode.Create, FileAccess.ReadWrite, FileShare.None, 8, FileOptions.None);

                // Write the number of bytes to the file.
                fWrite.WriteByte((byte)messageByte.Length);

                // Write the bytes to the file.
                fWrite.Write(messageByte, 0, messageByte.Length);

                // Close the stream.
                fWrite.Close();

                
                // Open a file and read the number of bytes.

                FileStream fRead = new FileStream("test.txt", FileMode.Open);

                // The first byte is the string length.
                int length = (int)fRead.ReadByte();

                // Create a new byte array for the data.
                byte[] readBytes = new byte[length];

                // Read the data from the file.
                fRead.Read(readBytes, 0, readBytes.Length);

                // Close the stream.
                fRead.Close();

                // Display the data.
                Console.WriteLine(Encoding.ASCII.GetString(readBytes));

                Console.WriteLine("Done writing and reading data.");
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
            }

            Console.ReadLine();
        }
    }
}

Imports System
Imports System.IO
Imports System.Text
Imports System.Security.AccessControl



Module FileStreamExample

    Sub Main()
        Try
            ' Create a file and write data to it.
            ' Create an array of bytes.
            Dim messageByte As Byte() = Encoding.ASCII.GetBytes("Here is some data.")

            ' Create a file using the FileStream class.
            Dim fWrite As New FileStream("test.txt", FileMode.Create, FileAccess.ReadWrite, FileShare.None, 8, FileOptions.None)

            ' Write the number of bytes to the file.
            fWrite.WriteByte(System.Convert.ToByte(messageByte.Length))

            ' Write the bytes to the file.
            fWrite.Write(messageByte, 0, messageByte.Length)

            ' Close the stream.
            fWrite.Close()


            ' Open a file and read the number of bytes.
            Dim fRead As New FileStream("test.txt", FileMode.Open)

            ' The first byte is the string length.
            Dim length As Integer = Fix(fRead.ReadByte())

            ' Create a new byte array for the data.
            Dim readBytes(length) As Byte

            ' Read the data from the file.
            fRead.Read(readBytes, 0, readBytes.Length)

            ' Close the stream.
            fRead.Close()

            ' Display the data.
            Console.WriteLine(Encoding.ASCII.GetString(readBytes))

            Console.WriteLine("Done writing and reading data.")
        Catch e As Exception
            Console.WriteLine(e)
        End Try

        Console.ReadLine()

    End Sub
End Module

Remarks

The .NET Framework does not support direct access to physical disks through paths that are device names, such as "\\.\PHYSICALDRIVE0 ".

The fileOptions parameter is used to provide access to more advanced operations that can be leveraged when creating a FileStream object.

The path parameter can be a file name, including a file on a Universal Naming Convention (UNC) share.

Note

path is not required to be a file stored on disk; it can be any part of a system that supports access through streams. For example, depending on the system, this class can access a physical device.

CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the CanSeek property on the resulting FileStream is false. For additional information, see CanSeek.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean) FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean) FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean) FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean)

Initializes a new instance of the FileStream class with the specified path, creation mode, read/write and sharing permission, buffer size, and synchronous or asynchronous state.

public:
 FileStream(System::String ^ path, System::IO::FileMode mode, System::IO::FileAccess access, System::IO::FileShare share, int bufferSize, bool useAsync);
public FileStream (string path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share, int bufferSize, bool useAsync);
new System.IO.FileStream : string * System.IO.FileMode * System.IO.FileAccess * System.IO.FileShare * int * bool -> System.IO.FileStream
Public Sub New (path As String, mode As FileMode, access As FileAccess, share As FileShare, bufferSize As Integer, useAsync As Boolean)

Parameters

path
String String String String

A relative or absolute path for the file that the current FileStream object will encapsulate.

mode
FileMode FileMode FileMode FileMode

A constant that determines how to open or create the file.

access
FileAccess FileAccess FileAccess FileAccess

A constant that determines how the file can be accessed by the FileStream object. This also determines the values returned by the CanRead and CanWrite properties of the FileStream object. CanSeek is true if path specifies a disk file.

share
FileShare FileShare FileShare FileShare

A constant that determines how the file will be shared by processes.

bufferSize
Int32 Int32 Int32 Int32

A positive Int32 value greater than 0 indicating the buffer size. The default buffer size is 4096..

useAsync
Boolean Boolean Boolean Boolean

Specifies whether to use asynchronous I/O or synchronous I/O. However, note that the underlying operating system might not support asynchronous I/O, so when specifying true, the handle might be opened synchronously depending on the platform. When opened asynchronously, the BeginRead(Byte[], Int32, Int32, AsyncCallback, Object) and BeginWrite(Byte[], Int32, Int32, AsyncCallback, Object) methods perform better on large reads or writes, but they might be much slower for small reads or writes. If the application is designed to take advantage of asynchronous I/O, set the useAsync parameter to true. Using asynchronous I/O correctly can speed up applications by as much as a factor of 10, but using it without redesigning the application for asynchronous I/O can decrease performance by as much as a factor of 10.

Exceptions

path is an empty string (""), contains only white space, or contains one or more invalid characters.

-or-

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in an NTFS environment.

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in a non-NTFS environment.

bufferSize is negative or zero.

-or-

mode, access, or share contain an invalid value.

The file cannot be found, such as when mode is FileMode.Truncate or FileMode.Open, and the file specified by path does not exist. The file must already exist in these modes.

An I/O error, such as specifying FileMode.CreateNew when the file specified by path already exists, occurred.

-or-

The system is running Windows 98 or Windows 98 Second Edition and share is set to FileShare.Delete.

-or-

The stream has been closed.

The caller does not have the required permission.

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

The access requested is not permitted by the operating system for the specified path, such as when access is Write or ReadWrite and the file or directory is set for read-only access.

The specified path, file name, or both exceed the system-defined maximum length.

Examples

The following code example shows how to asynchronously write data to a file and then verify that the data was written correctly. A State object is created to pass information from the main thread to the EndReadCallback and EndWriteCallback methods.

using namespace System;
using namespace System::IO;
using namespace System::Threading;

// Maintain state information to be passed to 
// EndWriteCallback and EndReadCallback.
ref class State
{
private:

   // fStream is used to read and write to the file.
   FileStream^ fStream;

   // writeArray stores data that is written to the file.
   array<Byte>^writeArray;

   // readArray stores data that is read from the file.
   array<Byte>^readArray;

   // manualEvent signals the main thread 
   // when verification is complete.
   ManualResetEvent^ manualEvent;

public:
   State( FileStream^ fStream, array<Byte>^writeArray, ManualResetEvent^ manualEvent )
   {
      this->fStream = fStream;
      this->writeArray = writeArray;
      this->manualEvent = manualEvent;
      readArray = gcnew array<Byte>(writeArray->Length);
   }


   property FileStream^ FStream 
   {
      FileStream^ get()
      {
         return fStream;
      }

   }

   property array<Byte>^ WriteArray 
   {
      array<Byte>^ get()
      {
         return writeArray;
      }

   }

   property array<Byte>^ ReadArray 
   {
      array<Byte>^ get()
      {
         return readArray;
      }

   }

   property ManualResetEvent^ ManualEvent 
   {
      ManualResetEvent^ get()
      {
         return manualEvent;
      }

   }

};

ref class FStream
{
private:

   // When BeginRead is finished reading data from the file, the 
   // EndReadCallback method is called to end the asynchronous 
   // read operation and then verify the data.
   static void EndReadCallback( IAsyncResult^ asyncResult )
   {
      State^ tempState = dynamic_cast<State^>(asyncResult->AsyncState);
      int readCount = tempState->FStream->EndRead( asyncResult );
      int i = 0;
      while ( i < readCount )
      {
         if ( tempState->ReadArray[ i ] != tempState->WriteArray[ i++ ] )
         {
            Console::WriteLine( "Error writing data." );
            tempState->FStream->Close();
            return;
         }
      }

      Console::WriteLine( "The data was written to {0} "
      "and verified.", tempState->FStream->Name );
      tempState->FStream->Close();
      
      // Signal the main thread that the verification is finished.
      tempState->ManualEvent->Set();
   }


public:

   // When BeginWrite is finished writing data to the file, the
   // EndWriteCallback method is called to end the asynchronous 
   // write operation and then read back and verify the data.
   static void EndWriteCallback( IAsyncResult^ asyncResult )
   {
      State^ tempState = dynamic_cast<State^>(asyncResult->AsyncState);
      FileStream^ fStream = tempState->FStream;
      fStream->EndWrite( asyncResult );
      
      // Asynchronously read back the written data.
      fStream->Position = 0;
      asyncResult = fStream->BeginRead( tempState->ReadArray, 0, tempState->ReadArray->Length, gcnew AsyncCallback( &FStream::EndReadCallback ), tempState );
      
      // Concurrently do other work, such as 
      // logging the write operation.
   }

};


int main()
{
   
   // Create a synchronization object that gets 
   // signaled when verification is complete.
   ManualResetEvent^ manualEvent = gcnew ManualResetEvent( false );
   
   // Create the data to write to the file.
   array<Byte>^writeArray = gcnew array<Byte>(100000);
   (gcnew Random)->NextBytes( writeArray );
   FileStream^ fStream = gcnew FileStream(  "Test#@@#.dat",FileMode::Create,FileAccess::ReadWrite,FileShare::None,4096,true );
   
   // Check that the FileStream was opened asynchronously.
   Console::WriteLine( "fStream was {0}opened asynchronously.", fStream->IsAsync ? (String^)"" : "not " );
   
   // Asynchronously write to the file.
   IAsyncResult^ asyncResult = fStream->BeginWrite( writeArray, 0, writeArray->Length, gcnew AsyncCallback( &FStream::EndWriteCallback ), gcnew State( fStream,writeArray,manualEvent ) );
   
   // Concurrently do other work and then wait 
   // for the data to be written and verified.
   manualEvent->WaitOne( 5000, false );
}

using System;
using System.IO;
using System.Threading;

class FStream
{
    static void Main()
    {
        // Create a synchronization object that gets 
        // signaled when verification is complete.
        ManualResetEvent manualEvent = new ManualResetEvent(false);

        // Create random data to write to the file.
        byte[] writeArray = new byte[100000];
        new Random().NextBytes(writeArray);

        FileStream fStream = 
            new FileStream("Test#@@#.dat", FileMode.Create, 
            FileAccess.ReadWrite, FileShare.None, 4096, true);

        // Check that the FileStream was opened asynchronously.
        Console.WriteLine("fStream was {0}opened asynchronously.",
            fStream.IsAsync ? "" : "not ");

        // Asynchronously write to the file.
        IAsyncResult asyncResult = fStream.BeginWrite(
            writeArray, 0, writeArray.Length, 
            new AsyncCallback(EndWriteCallback), 
            new State(fStream, writeArray, manualEvent));

        // Concurrently do other work and then wait 
        // for the data to be written and verified.
        manualEvent.WaitOne(5000, false);
    }

    // When BeginWrite is finished writing data to the file, the
    // EndWriteCallback method is called to end the asynchronous 
    // write operation and then read back and verify the data.
    static void EndWriteCallback(IAsyncResult asyncResult)
    {
        State tempState = (State)asyncResult.AsyncState;
        FileStream fStream = tempState.FStream;
        fStream.EndWrite(asyncResult);

        // Asynchronously read back the written data.
        fStream.Position = 0;
        asyncResult = fStream.BeginRead(
            tempState.ReadArray, 0 , tempState.ReadArray.Length, 
            new AsyncCallback(EndReadCallback), tempState);

        // Concurrently do other work, such as 
        // logging the write operation.
    }

    // When BeginRead is finished reading data from the file, the 
    // EndReadCallback method is called to end the asynchronous 
    // read operation and then verify the data.
    static void EndReadCallback(IAsyncResult asyncResult)
    {
        State tempState = (State)asyncResult.AsyncState;
        int readCount = tempState.FStream.EndRead(asyncResult);

        int i = 0;
        while(i < readCount)
        {
            if(tempState.ReadArray[i] != tempState.WriteArray[i++])
            {
                Console.WriteLine("Error writing data.");
                tempState.FStream.Close();
                return;
            }
        }
        Console.WriteLine("The data was written to {0} and verified.",
            tempState.FStream.Name);
        tempState.FStream.Close();

        // Signal the main thread that the verification is finished.
        tempState.ManualEvent.Set();
    }

    // Maintain state information to be passed to 
    // EndWriteCallback and EndReadCallback.
    class State
    {
        // fStream is used to read and write to the file.
        FileStream fStream;

        // writeArray stores data that is written to the file.
        byte[] writeArray;

        // readArray stores data that is read from the file.
        byte[] readArray;

        // manualEvent signals the main thread 
        // when verification is complete.
        ManualResetEvent manualEvent;

        public State(FileStream fStream, byte[] writeArray, 
            ManualResetEvent manualEvent)
        {
            this.fStream   = fStream;
            this.writeArray = writeArray;
            this.manualEvent = manualEvent;
            readArray = new byte[writeArray.Length];
        }

        public FileStream FStream
        { get{ return fStream; } }

        public byte[] WriteArray
        { get{ return writeArray; } }

        public byte[] ReadArray
        { get{ return readArray; } }

        public ManualResetEvent ManualEvent
        { get{ return manualEvent; } }
    }
}
Imports System
Imports System.IO
Imports System.Threading

Class FStream

    Shared Sub Main()

        ' Create a synchronization object that gets 
        ' signaled when verification is complete.
        Dim manualEvent As New ManualResetEvent(False)

        ' Create random data to write to the file.
        Dim writeArray(100000) As Byte
        Dim randomGenerator As New Random()
        randomGenerator.NextBytes(writeArray)

        Dim fStream As New FileStream("Test#@@#.dat", _
            FileMode.Create, FileAccess.ReadWrite, _
            FileShare.None, 4096, True)

        ' Check that the FileStream was opened asynchronously.
        If fStream.IsAsync = True
            Console.WriteLine("fStream was opened asynchronously.")
        Else
            Console.WriteLine("fStream was not opened asynchronously.")
        End If

        ' Asynchronously write to the file.
        Dim asyncResult As IAsyncResult = fStream.BeginWrite( _
            writeArray, 0, writeArray.Length, _
            AddressOf EndWriteCallback , _
            New State(fStream, writeArray, manualEvent))

        ' Concurrently do other work and then wait
        ' for the data to be written and verified.
        manualEvent.WaitOne(5000, False)
    End Sub

    ' When BeginWrite is finished writing data to the file, the
    ' EndWriteCallback method is called to end the asynchronous 
    ' write operation and then read back and verify the data.
    Private Shared Sub EndWriteCallback(asyncResult As IAsyncResult)
        Dim tempState As State = _
            DirectCast(asyncResult.AsyncState, State)
        Dim fStream As FileStream = tempState.FStream
        fStream.EndWrite(asyncResult)

        ' Asynchronously read back the written data.
        fStream.Position = 0
        asyncResult = fStream.BeginRead( _ 
            tempState.ReadArray, 0 , tempState.ReadArray.Length, _
            AddressOf EndReadCallback, tempState)

        ' Concurrently do other work, such as 
        ' logging the write operation.
    End Sub

    ' When BeginRead is finished reading data from the file, the 
    ' EndReadCallback method is called to end the asynchronous 
    ' read operation and then verify the data.
   Private Shared Sub EndReadCallback(asyncResult As IAsyncResult)
        Dim tempState As State = _
            DirectCast(asyncResult.AsyncState, State)
        Dim readCount As Integer = _
            tempState.FStream.EndRead(asyncResult)

        Dim i As Integer = 0
        While(i < readCount)
            If(tempState.ReadArray(i) <> tempState.WriteArray(i))
                Console.WriteLine("Error writing data.")
                tempState.FStream.Close()
                Return
            End If
            i += 1
        End While

        Console.WriteLine("The data was written to {0} and " & _
            "verified.", tempState.FStream.Name)
        tempState.FStream.Close()

        ' Signal the main thread that the verification is finished.
        tempState.ManualEvent.Set()
    End Sub

    ' Maintain state information to be passed to 
    ' EndWriteCallback and EndReadCallback.
    Private Class State

        ' fStreamValue is used to read and write to the file.
        Dim fStreamValue As FileStream

        ' writeArrayValue stores data that is written to the file.
        Dim writeArrayValue As Byte()

        ' readArrayValue stores data that is read from the file.
        Dim readArrayValue As Byte()

        ' manualEvent signals the main thread 
        ' when verification is complete.
        Dim manualEventValue As ManualResetEvent 

        Sub New(aStream As FileStream, anArray As Byte(), _
            manualEvent As ManualResetEvent)

            fStreamValue     = aStream
            writeArrayValue  = anArray
            manualEventValue = manualEvent
            readArrayValue   = New Byte(anArray.Length - 1){}
        End Sub    

            Public ReadOnly Property FStream() As FileStream
                Get
                    Return fStreamValue
                End Get
            End Property

            Public ReadOnly Property WriteArray() As Byte()
                Get
                    Return writeArrayValue
                End Get
            End Property

            Public ReadOnly Property ReadArray() As Byte()
                Get
                    Return readArrayValue
                End Get
            End Property

            Public ReadOnly Property ManualEvent() As ManualResetEvent
                Get
                    Return manualEventValue
                End Get
            End Property
    End Class 
   
End Class

Remarks

The .NET Framework does not support direct access to physical disks through paths that are device names, such as "\\.\PHYSICALDRIVE0 ".

The path parameter can be a file name, including a file on a Universal Naming Convention (UNC) share.

Note

path is not required to be a file stored on disk; it can be any part of a system that supports access through streams. For example, depending on the system, this class can access a physical device.

CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the CanSeek property on the resulting FileStream is false. For additional information, see CanSeek.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(IntPtr, FileAccess, Boolean, Int32, Boolean) FileStream(IntPtr, FileAccess, Boolean, Int32, Boolean) FileStream(IntPtr, FileAccess, Boolean, Int32, Boolean) FileStream(IntPtr, FileAccess, Boolean, Int32, Boolean)

Warning

This API is now obsolete.

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission, FileStream instance ownership, buffer size, and synchronous or asynchronous state.

public:
 FileStream(IntPtr handle, System::IO::FileAccess access, bool ownsHandle, int bufferSize, bool isAsync);
[System.Obsolete("Use FileStream(SafeFileHandle handle, FileAccess access, int bufferSize, bool isAsync) instead")]
[System.Obsolete("This constructor has been deprecated.  Please use new FileStream(SafeFileHandle handle, FileAccess access, int bufferSize, bool isAsync) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed.  http://go.microsoft.com/fwlink/?linkid=14202")]
public FileStream (IntPtr handle, System.IO.FileAccess access, bool ownsHandle, int bufferSize, bool isAsync);
new System.IO.FileStream : nativeint * System.IO.FileAccess * bool * int * bool -> System.IO.FileStream
Public Sub New (handle As IntPtr, access As FileAccess, ownsHandle As Boolean, bufferSize As Integer, isAsync As Boolean)

Parameters

handle
IntPtr IntPtr IntPtr IntPtr

A file handle for the file that this FileStream object will encapsulate.

access
FileAccess FileAccess FileAccess FileAccess

A constant that sets the CanRead and CanWrite properties of the FileStream object.

ownsHandle
Boolean Boolean Boolean Boolean

true if the file handle will be owned by this FileStream instance; otherwise, false.

bufferSize
Int32 Int32 Int32 Int32

A positive Int32 value greater than 0 indicating the buffer size. The default buffer size is 4096.

isAsync
Boolean Boolean Boolean Boolean

true if the handle was opened asynchronously (that is, in overlapped I/O mode); otherwise, false.

Exceptions

access is less than FileAccess.Read or greater than FileAccess.ReadWrite or bufferSize is less than or equal to 0.

An I/O error, such as a disk error, occurred.

-or-

The stream has been closed.

The caller does not have the required permission.

The access requested is not permitted by the operating system for the specified file handle, such as when access is Write or ReadWrite and the file handle is set for read-only access.

Remarks

The FileStream object is given the specified access to the file. The ownership of the handle will be as specified. If this FileStream owns the handle, a call to the Close method will also close the handle. In particular, the file's handle count is decremented. The FileStream object is given the specified buffer size.

FileStream assumes that it has exclusive control over the handle. Reading, writing, or seeking while a FileStream is also holding a handle could result in data corruption. For data safety, call Flush before using the handle, and avoid calling any methods other than Close after you are done using the handle. Alternately, read and write to the handle before calling this FileStream constructor.

FileShare.Read is the default for those FileStream constructors without a FileShare parameter.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

SecurityPermission
for access to unmanaged code. Associated enumeration: UnmanagedCode.

See Also

FileStream(String, FileMode, FileAccess, FileShare) FileStream(String, FileMode, FileAccess, FileShare) FileStream(String, FileMode, FileAccess, FileShare) FileStream(String, FileMode, FileAccess, FileShare)

Initializes a new instance of the FileStream class with the specified path, creation mode, read/write permission, and sharing permission.

public:
 FileStream(System::String ^ path, System::IO::FileMode mode, System::IO::FileAccess access, System::IO::FileShare share);
public FileStream (string path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share);
new System.IO.FileStream : string * System.IO.FileMode * System.IO.FileAccess * System.IO.FileShare -> System.IO.FileStream
Public Sub New (path As String, mode As FileMode, access As FileAccess, share As FileShare)

Parameters

path
String String String String

A relative or absolute path for the file that the current FileStream object will encapsulate.

mode
FileMode FileMode FileMode FileMode

A constant that determines how to open or create the file.

access
FileAccess FileAccess FileAccess FileAccess

A constant that determines how the file can be accessed by the FileStream object. This also determines the values returned by the CanRead and CanWrite properties of the FileStream object. CanSeek is true if path specifies a disk file.

share
FileShare FileShare FileShare FileShare

A constant that determines how the file will be shared by processes.

Exceptions

path is an empty string (""), contains only white space, or contains one or more invalid characters.

-or-

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in an NTFS environment.

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in a non-NTFS environment.

The file cannot be found, such as when mode is FileMode.Truncate or FileMode.Open, and the file specified by path does not exist. The file must already exist in these modes.

An I/O error, such as specifying FileMode.CreateNew when the file specified by path already exists, occurred.

-or-

The system is running Windows 98 or Windows 98 Second Edition and share is set to FileShare.Delete.

-or-

The stream has been closed.

The caller does not have the required permission.

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

The access requested is not permitted by the operating system for the specified path, such as when access is Write or ReadWrite and the file or directory is set for read-only access.

The specified path, file name, or both exceed the system-defined maximum length.

Examples

This code example is part of a larger example provided for the Lock method.

FileStream^ fileStream = gcnew FileStream( "Test#@@#.dat",FileMode::OpenOrCreate,FileAccess::ReadWrite,FileShare::ReadWrite );

using(FileStream fileStream = new FileStream(
    "Test#@@#.dat", FileMode.OpenOrCreate, 
    FileAccess.ReadWrite, FileShare.ReadWrite))
Dim aFileStream As New FileStream( _
    "Test#@@#.dat", FileMode.OpenOrCreate, _
    FileAccess.ReadWrite, FileShare.ReadWrite)

Remarks

The .NET Framework does not support direct access to physical disks through paths that are device names, such as "\\.\PHYSICALDRIVE0 ".

The path parameter can be a file name, including a file on a Universal Naming Convention (UNC) share.

The constructor is given read/write access to the file, and it is opened sharing Read access (that is, requests to open the file for writing by this or another process will fail until the FileStream object has been closed, but read attempts will succeed). The buffer size is set to the default size of 4096 bytes (4 KB).

Note

path is not required to be a file stored on disk; it can be any part of a system that supports access through streams. For example, depending on the system, this class can access a physical device.

CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the CanSeek property on the resulting FileStream is false. For additional information, see CanSeek.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(String, FileMode, FileAccess, FileShare, Int32) FileStream(String, FileMode, FileAccess, FileShare, Int32) FileStream(String, FileMode, FileAccess, FileShare, Int32) FileStream(String, FileMode, FileAccess, FileShare, Int32)

Initializes a new instance of the FileStream class with the specified path, creation mode, read/write and sharing permission, and buffer size.

public:
 FileStream(System::String ^ path, System::IO::FileMode mode, System::IO::FileAccess access, System::IO::FileShare share, int bufferSize);
public FileStream (string path, System.IO.FileMode mode, System.IO.FileAccess access, System.IO.FileShare share, int bufferSize);
new System.IO.FileStream : string * System.IO.FileMode * System.IO.FileAccess * System.IO.FileShare * int -> System.IO.FileStream
Public Sub New (path As String, mode As FileMode, access As FileAccess, share As FileShare, bufferSize As Integer)

Parameters

path
String String String String

A relative or absolute path for the file that the current FileStream object will encapsulate.

mode
FileMode FileMode FileMode FileMode

A constant that determines how to open or create the file.

access
FileAccess FileAccess FileAccess FileAccess

A constant that determines how the file can be accessed by the FileStream object. This also determines the values returned by the CanRead and CanWrite properties of the FileStream object. CanSeek is true if path specifies a disk file.

share
FileShare FileShare FileShare FileShare

A constant that determines how the file will be shared by processes.

bufferSize
Int32 Int32 Int32 Int32

A positive Int32 value greater than 0 indicating the buffer size. The default buffer size is 4096.

Exceptions

path is an empty string (""), contains only white space, or contains one or more invalid characters.

-or-

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in an NTFS environment.

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in a non-NTFS environment.

bufferSize is negative or zero.

-or-

mode, access, or share contain an invalid value.

The file cannot be found, such as when mode is FileMode.Truncate or FileMode.Open, and the file specified by path does not exist. The file must already exist in these modes.

An I/O error, such as specifying FileMode.CreateNew when the file specified by path already exists, occurred.

-or-

The system is running Windows 98 or Windows 98 Second Edition and share is set to FileShare.Delete.

-or-

The stream has been closed.

The caller does not have the required permission.

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

The access requested is not permitted by the operating system for the specified path, such as when access is Write or ReadWrite and the file or directory is set for read-only access.

The specified path, file name, or both exceed the system-defined maximum length.

Remarks

The .NET Framework does not support direct access to physical disks through paths that are device names, such as "\\.\PHYSICALDRIVE0 ".

The path parameter can be a file name, including a file on a Universal Naming Convention (UNC) share.

Note

path is not required to be a file stored on disk; it can be any part of a system that supports access through streams. For example, depending on the system, this class can access a physical device.

CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the CanSeek property on the resulting FileStream is false. For additional information, see CanSeek.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(SafeFileHandle, FileAccess, Int32, Boolean) FileStream(SafeFileHandle, FileAccess, Int32, Boolean) FileStream(SafeFileHandle, FileAccess, Int32, Boolean) FileStream(SafeFileHandle, FileAccess, Int32, Boolean)

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission, buffer size, and synchronous or asynchronous state.

public:
 FileStream(Microsoft::Win32::SafeHandles::SafeFileHandle ^ handle, System::IO::FileAccess access, int bufferSize, bool isAsync);
public FileStream (Microsoft.Win32.SafeHandles.SafeFileHandle handle, System.IO.FileAccess access, int bufferSize, bool isAsync);
new System.IO.FileStream : Microsoft.Win32.SafeHandles.SafeFileHandle * System.IO.FileAccess * int * bool -> System.IO.FileStream
Public Sub New (handle As SafeFileHandle, access As FileAccess, bufferSize As Integer, isAsync As Boolean)

Parameters

handle
SafeFileHandle SafeFileHandle SafeFileHandle SafeFileHandle

A file handle for the file that this FileStream object will encapsulate.

access
FileAccess FileAccess FileAccess FileAccess

A constant that sets the CanRead and CanWrite properties of the FileStream object.

bufferSize
Int32 Int32 Int32 Int32

A positive Int32 value greater than 0 indicating the buffer size. The default buffer size is 4096.

isAsync
Boolean Boolean Boolean Boolean

true if the handle was opened asynchronously (that is, in overlapped I/O mode); otherwise, false.

Exceptions

The handle parameter is an invalid handle.

-or-

The handle parameter is a synchronous handle and it was used asynchronously.

An I/O error, such as a disk error, occurred.

-or-

The stream has been closed.

The caller does not have the required permission.

The access requested is not permitted by the operating system for the specified file handle, such as when access is Write or ReadWrite and the file handle is set for read-only access.

Remarks

You set the isAsync parameter to true to open the file handle asynchronously. When the parameter is true, the stream utilizes overlapped I/O to perform file operations asynchronously. However, the parameter does not have to be true to call the ReadAsync, WriteAsync, or CopyToAsync method. When the isAsync parameter is false and you call the asynchronous read and write operations, the UI thread is still not blocked, but the actual I/O operation is performed synchronously.

FileStream assumes that it has exclusive control over the handle. Reading, writing, or seeking while a FileStream is also holding a handle could result in data corruption. For data safety, call Flush before using the handle, and avoid calling any methods other than Close after you are done using the handle. Alternately, read and write to the handle before calling this FileStream constructor.

FileShare.Read is the default for those FileStream constructors without a FileShare parameter.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

SecurityPermission
for permission to call unmanaged code. Associated enumerations: UnmanagedCode

See Also

FileStream(String, FileMode, FileAccess) FileStream(String, FileMode, FileAccess) FileStream(String, FileMode, FileAccess) FileStream(String, FileMode, FileAccess)

Initializes a new instance of the FileStream class with the specified path, creation mode, and read/write permission.

public:
 FileStream(System::String ^ path, System::IO::FileMode mode, System::IO::FileAccess access);
public FileStream (string path, System.IO.FileMode mode, System.IO.FileAccess access);
new System.IO.FileStream : string * System.IO.FileMode * System.IO.FileAccess -> System.IO.FileStream
Public Sub New (path As String, mode As FileMode, access As FileAccess)

Parameters

path
String String String String

A relative or absolute path for the file that the current FileStream object will encapsulate.

mode
FileMode FileMode FileMode FileMode

A constant that determines how to open or create the file.

access
FileAccess FileAccess FileAccess FileAccess

A constant that determines how the file can be accessed by the FileStream object. This also determines the values returned by the CanRead and CanWrite properties of the FileStream object. CanSeek is true if path specifies a disk file.

Exceptions

path is an empty string (""), contains only white space, or contains one or more invalid characters.

-or-

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in an NTFS environment.

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in a non-NTFS environment.

The file cannot be found, such as when mode is FileMode.Truncate or FileMode.Open, and the file specified by path does not exist. The file must already exist in these modes.

An I/O error, such as specifying FileMode.CreateNew when the file specified by path already exists, occurred.

-or-

The stream has been closed.

The caller does not have the required permission.

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

The access requested is not permitted by the operating system for the specified path, such as when access is Write or ReadWrite and the file or directory is set for read-only access.

The specified path, file name, or both exceed the system-defined maximum length.

Remarks

The .NET Framework does not support direct access to physical disks through paths that are device names, such as "\\.\PHYSICALDRIVE0 ".

The path parameter can be a file name, including a file on a Universal Naming Convention (UNC) share.

The constructor is given read/write access to the file, and it is opened sharing Read access (that is, requests to open the file for writing by this or another process will fail until the FileStream object has been closed, but read attempts will succeed). The buffer size is set to the default size of 4096 bytes (4 KB).

Note

path is not required to be a file stored on disk; it can be any part of a system that supports access through streams. For example, depending on the system, this class can access a physical device.

CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the CanSeek property on the resulting FileStream is false. For additional information, see CanSeek.

FileShare.Read is the default for those FileStream constructors without a FileShare parameter.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(IntPtr, FileAccess, Boolean) FileStream(IntPtr, FileAccess, Boolean) FileStream(IntPtr, FileAccess, Boolean) FileStream(IntPtr, FileAccess, Boolean)

Warning

This API is now obsolete.

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission and FileStream instance ownership.

public:
 FileStream(IntPtr handle, System::IO::FileAccess access, bool ownsHandle);
[System.Obsolete("Use FileStream(SafeFileHandle handle, FileAccess access) instead")]
[System.Obsolete("This constructor has been deprecated.  Please use new FileStream(SafeFileHandle handle, FileAccess access) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed.  http://go.microsoft.com/fwlink/?linkid=14202")]
public FileStream (IntPtr handle, System.IO.FileAccess access, bool ownsHandle);
new System.IO.FileStream : nativeint * System.IO.FileAccess * bool -> System.IO.FileStream
Public Sub New (handle As IntPtr, access As FileAccess, ownsHandle As Boolean)

Parameters

handle
IntPtr IntPtr IntPtr IntPtr

A file handle for the file that the current FileStream object will encapsulate.

access
FileAccess FileAccess FileAccess FileAccess

A constant that sets the CanRead and CanWrite properties of the FileStream object.

ownsHandle
Boolean Boolean Boolean Boolean

true if the file handle will be owned by this FileStream instance; otherwise, false.

Exceptions

The caller does not have the required permission.

An I/O error, such as a disk error, occurred.

-or-

The stream has been closed.

The access requested is not permitted by the operating system for the specified file handle, such as when access is Write or ReadWrite and the file handle is set for read-only access.

Remarks

The FileStream object is given the specified access to the file. The ownership of the handle will be as specified. If this process owns the handle, a call to the Close method will also close the handle and the file's handle count is decremented. The FileStream object is given the default buffer size of 4096 bytes.

FileStream assumes that it has exclusive control over the handle. Reading, writing, or seeking while a FileStream is also holding a handle could result in data corruption. For data safety, call Flush before using the handle, and avoid calling methods other than Close after you are done using the handle.

FileShare.Read is the default for those FileStream constructors without a FileShare parameter.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(SafeFileHandle, FileAccess, Int32) FileStream(SafeFileHandle, FileAccess, Int32) FileStream(SafeFileHandle, FileAccess, Int32) FileStream(SafeFileHandle, FileAccess, Int32)

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission, and buffer size.

public:
 FileStream(Microsoft::Win32::SafeHandles::SafeFileHandle ^ handle, System::IO::FileAccess access, int bufferSize);
public FileStream (Microsoft.Win32.SafeHandles.SafeFileHandle handle, System.IO.FileAccess access, int bufferSize);
new System.IO.FileStream : Microsoft.Win32.SafeHandles.SafeFileHandle * System.IO.FileAccess * int -> System.IO.FileStream
Public Sub New (handle As SafeFileHandle, access As FileAccess, bufferSize As Integer)

Parameters

handle
SafeFileHandle SafeFileHandle SafeFileHandle SafeFileHandle

A file handle for the file that the current FileStream object will encapsulate.

access
FileAccess FileAccess FileAccess FileAccess

A FileAccess constant that sets the CanRead and CanWrite properties of the FileStream object.

bufferSize
Int32 Int32 Int32 Int32

A positive Int32 value greater than 0 indicating the buffer size. The default buffer size is 4096.

Exceptions

The handle parameter is an invalid handle.

-or-

The handle parameter is a synchronous handle and it was used asynchronously.

An I/O error, such as a disk error, occurred.

-or-

The stream has been closed.

The caller does not have the required permission.

The access requested is not permitted by the operating system for the specified file handle, such as when access is Write or ReadWrite and the file handle is set for read-only access.

Remarks

FileStream assumes that it has exclusive control over the handle. Reading, writing, or seeking while a FileStream is also holding a handle could result in data corruption. For data safety, call Flush before using the handle, and avoid calling any methods other than Close after you are done using the handle. Alternately, read and write to the handle before calling this FileStream constructor.

FileShare.Read is the default for those FileStream constructors without a FileShare parameter.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

SecurityPermission
for permission to call unmanaged code. Associated enumerations: UnmanagedCode

See Also

FileStream(String, FileMode) FileStream(String, FileMode) FileStream(String, FileMode) FileStream(String, FileMode)

Initializes a new instance of the FileStream class with the specified path and creation mode.

public:
 FileStream(System::String ^ path, System::IO::FileMode mode);
public FileStream (string path, System.IO.FileMode mode);
new System.IO.FileStream : string * System.IO.FileMode -> System.IO.FileStream
Public Sub New (path As String, mode As FileMode)

Parameters

path
String String String String

A relative or absolute path for the file that the current FileStream object will encapsulate.

mode
FileMode FileMode FileMode FileMode

A constant that determines how to open or create the file.

Exceptions

path is an empty string (""), contains only white space, or contains one or more invalid characters.

-or-

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in an NTFS environment.

path refers to a non-file device, such as "con:", "com1:", "lpt1:", etc. in a non-NTFS environment.

The caller does not have the required permission.

The file cannot be found, such as when mode is FileMode.Truncate or FileMode.Open, and the file specified by path does not exist. The file must already exist in these modes.

An I/O error, such as specifying FileMode.CreateNew when the file specified by path already exists, occurred.

-or-

The stream has been closed.

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

The specified path, file name, or both exceed the system-defined maximum length.

Examples

The following code example shows how to write data to a file, byte by byte, and then verify that the data was written correctly.

using namespace System;
using namespace System::IO;
int main()
{
   String^ fileName =  "Test@##@.dat";
   
   // Create random data to write to the file.
   array<Byte>^dataArray = gcnew array<Byte>(100000);
   (gcnew Random)->NextBytes( dataArray );
   FileStream^ fileStream = gcnew FileStream( fileName,FileMode::Create );
   try
   {
      
      // Write the data to the file, byte by byte.
      for ( int i = 0; i < dataArray->Length; i++ )
      {
         fileStream->WriteByte( dataArray[ i ] );

      }
      
      // Set the stream position to the beginning of the file.
      fileStream->Seek( 0, SeekOrigin::Begin );
      
      // Read and verify the data.
      for ( int i = 0; i < fileStream->Length; i++ )
      {
         if ( dataArray[ i ] != fileStream->ReadByte() )
         {
            Console::WriteLine( "Error writing data." );
            return  -1;
         }

      }
      Console::WriteLine( "The data was written to {0} "
      "and verified.", fileStream->Name );
   }
   finally
   {
      fileStream->Close();
   }

}

using System;
using System.IO;

class FStream
{
    static void Main()
    {
        const string fileName = "Test#@@#.dat";

        // Create random data to write to the file.
        byte[] dataArray = new byte[100000];
        new Random().NextBytes(dataArray);

        using(FileStream  
            fileStream = new FileStream(fileName, FileMode.Create))
        {
            // Write the data to the file, byte by byte.
            for(int i = 0; i < dataArray.Length; i++)
            {
                fileStream.WriteByte(dataArray[i]);
            }

            // Set the stream position to the beginning of the file.
            fileStream.Seek(0, SeekOrigin.Begin);

            // Read and verify the data.
            for(int i = 0; i < fileStream.Length; i++)
            {
                if(dataArray[i] != fileStream.ReadByte())
                {
                    Console.WriteLine("Error writing data.");
                    return;
                }
            }
            Console.WriteLine("The data was written to {0} " +
                "and verified.", fileStream.Name);
        }
    }
}
Imports Microsoft.VisualBasic
Imports System
Imports System.IO
Imports System.Text

Class FStream

    Shared Sub Main()

        Const fileName As String = "Test#@@#.dat"

        ' Create random data to write to the file.
        Dim dataArray(100000) As Byte
        Dim randomGenerator As New Random()
        randomGenerator.NextBytes(dataArray)

        Dim fileStream As FileStream = _
            new FileStream(fileName, FileMode.Create)
        Try

            ' Write the data to the file, byte by byte.
            For i As Integer = 0 To dataArray.Length - 1
                fileStream.WriteByte(dataArray(i))
            Next i

            ' Set the stream position to the beginning of the stream.
            fileStream.Seek(0, SeekOrigin.Begin)

            ' Read and verify the data.
            For i As Integer = 0 To _
                CType(fileStream.Length, Integer) - 1

                If dataArray(i) <> fileStream.ReadByte() Then
                    Console.WriteLine("Error writing data.")
                    Return
                End If
            Next i
            Console.WriteLine("The data was written to {0} " & _
                "and verified.", fileStream.Name)
        Finally
            fileStream.Close()
        End Try
    
    End Sub
End Class

Remarks

The .NET Framework does not support direct access to physical disks through paths that are device names, such as "\\.\PHYSICALDRIVE0 ".

The path parameter can be a file name, including a file on a Universal Naming Convention (UNC) share.

The constructor is given read/write access to the file, and it is opened sharing Read access (that is, requests to open the file for writing by this or another process will fail until the FileStream object has been closed, but read attempts will succeed).

You cannot use this constructor to open read-only files; instead, you must use a constructor that accepts a FileAccess parameter with the value set to FileAccess.Read.

The buffer size is set to the default size of 4096 bytes (4 KB).

Note

path is not required to be a file stored on disk; it can be any part of a system that supports access through streams. For example, depending on the system, this class can access a physical device.

CanSeek is true for all FileStream objects that encapsulate files. If path indicates a device that does not support seeking, the CanSeek property on the resulting FileStream is false. For additional information, see CanSeek.

FileShare.Read is the default for those FileStream constructors without a FileShare parameter.

For constructors without a FileAccess parameter, if the mode parameter is set to Append, Write is the default access. Otherwise, the access is set to ReadWrite.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(IntPtr, FileAccess) FileStream(IntPtr, FileAccess) FileStream(IntPtr, FileAccess) FileStream(IntPtr, FileAccess)

Warning

This API is now obsolete.

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission.

public:
 FileStream(IntPtr handle, System::IO::FileAccess access);
[System.Obsolete("Use FileStream(SafeFileHandle handle, FileAccess access) instead")]
[System.Obsolete("This constructor has been deprecated.  Please use new FileStream(SafeFileHandle handle, FileAccess access) instead.  http://go.microsoft.com/fwlink/?linkid=14202")]
public FileStream (IntPtr handle, System.IO.FileAccess access);
new System.IO.FileStream : nativeint * System.IO.FileAccess -> System.IO.FileStream
Public Sub New (handle As IntPtr, access As FileAccess)

Parameters

handle
IntPtr IntPtr IntPtr IntPtr

A file handle for the file that the current FileStream object will encapsulate.

access
FileAccess FileAccess FileAccess FileAccess

A constant that sets the CanRead and CanWrite properties of the FileStream object.

Exceptions

The caller does not have the required permission.

An I/O error, such as a disk error, occurred.

-or-

The stream has been closed.

The access requested is not permitted by the operating system for the specified file handle, such as when access is Write or ReadWrite and the file handle is set for read-only access.

Remarks

When Close is called, the handle is also closed and the file's handle count is decremented.

FileStream assumes that it has exclusive control over the handle. Reading, writing, or seeking while a FileStream is also holding a handle could result in data corruption. For data safety, call Flush before using the handle, and avoid calling any methods other than Close after you are done using the handle.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

FileShare.Read is the default for those FileStream constructors without a FileShare parameter.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

FileStream(IntPtr, FileAccess, Boolean, Int32) FileStream(IntPtr, FileAccess, Boolean, Int32) FileStream(IntPtr, FileAccess, Boolean, Int32) FileStream(IntPtr, FileAccess, Boolean, Int32)

Warning

This API is now obsolete.

Initializes a new instance of the FileStream class for the specified file handle, with the specified read/write permission, FileStream instance ownership, and buffer size.

public:
 FileStream(IntPtr handle, System::IO::FileAccess access, bool ownsHandle, int bufferSize);
[System.Obsolete("Use FileStream(SafeFileHandle handle, FileAccess access, int bufferSize) instead")]
[System.Obsolete("This constructor has been deprecated.  Please use new FileStream(SafeFileHandle handle, FileAccess access, int bufferSize) instead, and optionally make a new SafeFileHandle with ownsHandle=false if needed.  http://go.microsoft.com/fwlink/?linkid=14202")]
public FileStream (IntPtr handle, System.IO.FileAccess access, bool ownsHandle, int bufferSize);
new System.IO.FileStream : nativeint * System.IO.FileAccess * bool * int -> System.IO.FileStream
Public Sub New (handle As IntPtr, access As FileAccess, ownsHandle As Boolean, bufferSize As Integer)

Parameters

handle
IntPtr IntPtr IntPtr IntPtr

A file handle for the file that this FileStream object will encapsulate.

access
FileAccess FileAccess FileAccess FileAccess

A constant that sets the CanRead and CanWrite properties of the FileStream object.

ownsHandle
Boolean Boolean Boolean Boolean

true if the file handle will be owned by this FileStream instance; otherwise, false.

bufferSize
Int32 Int32 Int32 Int32

A positive Int32 value greater than 0 indicating the buffer size. The default buffer size is 4096.

Exceptions

An I/O error, such as a disk error, occurred.

-or-

The stream has been closed.

The caller does not have the required permission.

The access requested is not permitted by the operating system for the specified file handle, such as when access is Write or ReadWrite and the file handle is set for read-only access.

Remarks

The FileStream object is given the specified access to the file. The ownership of the handle will be as specified. If this FileStream owns the handle, a call to the Close method will also close the handle. In particular, the file's handle count is decremented. The FileStream object is given the specified buffer size.

FileStream assumes that it has exclusive control over the handle. Reading, writing, or seeking while a FileStream is also holding a handle could result in data corruption. For data safety, call Flush before using the handle, and avoid calling any methods other than Close after you are done using the handle. Alternately, read and write to the handle before calling this FileStream constructor.

FileShare.Read is the default for those FileStream constructors without a FileShare parameter.

Caution

When you compile a set of characters with a particular cultural setting and retrieve those same characters with a different cultural setting, the characters might not be interpretable, and could cause an exception to be thrown.

For a list of common file and directory operations, see Common I/O Tasks.

Security

FileIOPermission
for reading, writing, and appending to files. Associated enumerations: Read, Write, and Append.

See Also

Applies to