FileSystem.Lock Method

Definition

Namespace:

Microsoft.VisualBasic

Assembly:

Microsoft.VisualBasic.Core.dll

Controls access by other processes to all or part of a file opened by using the Open function. The My feature gives you better productivity and performance in file I/O operations than Lock and Unlock. For more information, see FileSystem.

Overloads

Lock(Int32)	Controls access by other processes to all or part of a file opened by using the Open function. The My feature gives you better productivity and performance in file I/O operations than Lock and Unlock. For more information, see FileSystem.
Lock(Int32, Int64)	Controls access by other processes to all or part of a file opened by using the Open function. The My feature gives you better productivity and performance in file I/O operations than Lock and Unlock. For more information, see FileSystem.
Lock(Int32, Int64, Int64)	Controls access by other processes to all or part of a file opened by using the Open function. The My feature gives you better productivity and performance in file I/O operations than Lock and Unlock. For more information, see FileSystem.

Lock(Int32)

Source:

FileSystem.vb

Controls access by other processes to all or part of a file opened by using the Open function. The My feature gives you better productivity and performance in file I/O operations than Lock and Unlock. For more information, see FileSystem.

public:
 static void Lock(int FileNumber);

[System.Runtime.Versioning.UnsupportedOSPlatform("ios")]
[System.Runtime.Versioning.UnsupportedOSPlatform("macos")]
[System.Runtime.Versioning.UnsupportedOSPlatform("tvos")]
public static void Lock (int FileNumber);

[<System.Runtime.Versioning.UnsupportedOSPlatform("ios")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("macos")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("tvos")>]
static member Lock : int -> unit

Public Sub Lock (FileNumber As Integer)

Parameters

FileNumber

Int32

Required. Any valid file number.

Attributes

UnsupportedOSPlatformAttribute

Exceptions

IOException

File mode is invalid.

Examples

This example illustrates the use of the Lock and Unlock functions. This example assumes that People.txt is a file that contains records of the structure Person.

Structure Person
    Dim Name As String
    Dim ID As Integer
End Structure

Sub PutInLockedFile(ByVal onePerson As Person)
    FileOpen(1, "c:\people.txt", OpenMode.Binary)
    Lock(1)
    FilePut(1, onePerson)
    Unlock(1)
    FileClose(1)
End Sub

Remarks

The Lock and Unlock functions are used in environments where several processes might need access to the same file.

Lock and Unlock functions are always used in pairs. The arguments to Lock and Unlock must be identical.

If Record, or FromRecord and ToRecord are not supplied, the lock will be for the whole file. If Record alone is specified the single record will be locked/unlocked.

If the file has been opened for sequential input or output, Lock and Unlock affect the whole file, regardless of the range specified by FromRecord andToRecord.

See also

• FileOpen(Int32, String, OpenMode, OpenAccess, OpenShare, Int32)
• IOException
• File Access with Visual Basic

Lock(Int32, Int64)

Source:

FileSystem.vb

Controls access by other processes to all or part of a file opened by using the Open function. The My feature gives you better productivity and performance in file I/O operations than Lock and Unlock. For more information, see FileSystem.

public:
 static void Lock(int FileNumber, long Record);

[System.Runtime.Versioning.UnsupportedOSPlatform("ios")]
[System.Runtime.Versioning.UnsupportedOSPlatform("macos")]
[System.Runtime.Versioning.UnsupportedOSPlatform("tvos")]
public static void Lock (int FileNumber, long Record);

[<System.Runtime.Versioning.UnsupportedOSPlatform("ios")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("macos")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("tvos")>]
static member Lock : int * int64 -> unit

Public Sub Lock (FileNumber As Integer, Record As Long)

Parameters

FileNumber

Int32

Required. Any valid file number.

Record

Int64

Optional. Number of the only record or byte to lock or unlock.

Attributes

UnsupportedOSPlatformAttribute

Exceptions

IOException

File mode is invalid.

Examples

This example illustrates the use of the Lock and Unlock functions. This example assumes that People.txt is a file that contains records of the structure Person.

Structure Person
    Dim Name As String
    Dim ID As Integer
End Structure

Sub PutInLockedFile(ByVal onePerson As Person)
    FileOpen(1, "c:\people.txt", OpenMode.Binary)
    Lock(1)
    FilePut(1, onePerson)
    Unlock(1)
    FileClose(1)
End Sub

Remarks

The Lock and Unlock functions are used in environments where several processes might need access to the same file.

Lock and Unlock functions are always used in pairs. The arguments to Lock and Unlock must be identical.

If Record, or FromRecord and ToRecord are not supplied, the lock will be for the whole file. If Record alone is specified the single record will be locked/unlocked.

If the file has been opened for sequential input or output, Lock and Unlock affect the whole file, regardless of the range specified by FromRecord andToRecord.

See also

• FileOpen(Int32, String, OpenMode, OpenAccess, OpenShare, Int32)
• IOException
• File Access with Visual Basic

Lock(Int32, Int64, Int64)

Source:

FileSystem.vb

Controls access by other processes to all or part of a file opened by using the Open function. The My feature gives you better productivity and performance in file I/O operations than Lock and Unlock. For more information, see FileSystem.

public:
 static void Lock(int FileNumber, long FromRecord, long ToRecord);

[System.Runtime.Versioning.UnsupportedOSPlatform("ios")]
[System.Runtime.Versioning.UnsupportedOSPlatform("macos")]
[System.Runtime.Versioning.UnsupportedOSPlatform("tvos")]
public static void Lock (int FileNumber, long FromRecord, long ToRecord);

[<System.Runtime.Versioning.UnsupportedOSPlatform("ios")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("macos")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("tvos")>]
static member Lock : int * int64 * int64 -> unit

Public Sub Lock (FileNumber As Integer, FromRecord As Long, ToRecord As Long)

Parameters

FileNumber

Int32

Required. Any valid file number.

FromRecord

Int64

Optional. Number of the first record or byte to lock or unlock.

ToRecord

Int64

Optional. Number of the last record or byte to lock or unlock.

Attributes

UnsupportedOSPlatformAttribute

Exceptions

IOException

File mode is invalid.

Examples

This example illustrates the use of the Lock and Unlock functions. This example assumes that People.txt is a file that contains records of the structure Person.

Structure Person
    Dim Name As String
    Dim ID As Integer
End Structure

Sub PutInLockedFile(ByVal onePerson As Person)
    FileOpen(1, "c:\people.txt", OpenMode.Binary)
    Lock(1)
    FilePut(1, onePerson)
    Unlock(1)
    FileClose(1)
End Sub

Remarks

The Lock and Unlock functions are used in environments where several processes might need access to the same file.

Lock and Unlock functions are always used in pairs. The arguments to Lock and Unlock must be identical.

If Record, or FromRecord and ToRecord are not supplied, the lock will be for the whole file. If Record alone is specified the single record will be locked/unlocked.

If the file has been opened for sequential input or output, Lock and Unlock affect the whole file, regardless of the range specified by FromRecord andToRecord.

See also

• FileOpen(Int32, String, OpenMode, OpenAccess, OpenShare, Int32)
• IOException
• File Access with Visual Basic