fUnlock (Function)

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Functions for managing external files

fUnlock

Presentation

Example

The unlock operation was not performed

Unlocking a file

Position in the file

Operating mode in Windows Vista (and later)

See also

Constants for the external files

Functions for managing external files

Handling the external files

Storing files in Android

Summary table: Managing the application directories according to the platform

fDetectRemovableStorage

fReadLineRegularExpression

fRemoveDir

fRename

fReportsAndQueriesDir

The unlock operation was not performed
Unlocking a file
Position in the file
Operating mode in Windows Vista (and later)

WINDEV

WEBDEV

WINDEV Mobile

Others

See also

fUnlock (Function)

In french: fDébloque

Entirely or partially unlocks an external file. The file was locked by fLock.

Caution: The unlock operation can be performed only if the section to unlock corresponds to the section locked.

Versions 18 and later

This function is now available in Windows Store apps mode.

New in version 18

This function is now available in Windows Store apps mode.

Versions 21 and later

This function is now available in Universal Windows 10 App mode.

New in version 21

This function is now available in Universal Windows 10 App mode.

Example

See additional examples

// Open an external file
FileID = fOpen("C:\MyDirectories\File.txt", foReadWrite)
IF FileID <> -1 THEN
// Lock the file
ResLock = fLock(FileID)
...
// Unlock the external file
ResUnlock = fUnlock(FileID)
END

Syntax

<Result> = fUnlock(<File identifier> [, <First byte to unlock> [, <Number of bytes to unlock>]])

<Result>: Boolean

True if the unlock operation was performed,
False otherwise.

<File identifier>: Integer

Identifier of the file to unlock, defined by fOpen or fCreate.

<First byte to unlock>: Optional integer

Position of the first byte (character) to unlock (0 corresponds to the first byte of the file).

<Number of bytes to unlock>: Optional integer

Number of bytes (characters) to unlock.

Remarks

The unlock operation was not performed

fUnlock returns False if the unlock operation was not performed. The unlock operation can be performed if:

the external file is opened.
the file identifier is valid.
the file or the bytes to unlock are identical to the locked ones. For example, if only a file section was locked, this same section must be unlocked. If the file was entirely locked, you cannot unlock a section of the file.
the file or the bytes to unlock have been locked by the same application and from the same computer.

Unlocking a file

The file is entirely unlocked if <First byte to unlock> and <Number of bytes to unlock> are not specified.
The file is unlocked from the first specified byte (<First byte to unlock>) to the end of file if <Number of bytes to unlock> is not specified.
A locked file (or partially locked file) is automatically unlocked when it is closed.

The lock is effective between two different sites or contexts. Unlike Windows, a process cannot lock a file that was previouly locked.

Position in the file

When opening a file, the current position corresponds to:

the first byte of the file (by default),
the last byte of the file if the file is opened in "addition" mode (foAdd constant).

This position can be modified by fSeek.

The current position is not modified by the execution of fUnlock.

Operating mode in Windows Vista (and later)

If this function does not operate properly in Windows Vista (and later), check whether the file used is not found in one of the system directories (Windows directory or "Program Files" directory).

Indeed, in Windows Vista (and later), with the UAC mechanism (User Account Control) enabled, you must have the administrator privileges to handle and/or modify the files found in the system directories (Windows directory or "Program Files" directory).

Programming tip: To handle and/or modify the files without having administrator privileges, you should:

avoid writing into the Windows directory or into the "Program Files" directory,
use the system directory corresponding to the application (returned by SysDir associated with the srCommonAppData constant).

Component : wd240std.dll