fWriteLine (Function)

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Ayuda / WLanguage / Funciones WLanguage / Funciones estándar / Funciones de archivos externos

Handling errors
Operating mode in Windows Vista (and later)
Position in the file
ANSI / Unicode management

WINDEV

WEBDEV

WINDEV Mobile

Otros

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fWriteLine (Function)

Writes a line to an external file. The characters required to go to the next line are automatically inserted at the end of the added line.

Only the ANSI format is supported.

Ejemplo

Ver ejemplos adicionales

// Open an external file
FileID is int
ResWrite is boolean
FileID = fOpen("C:\MyDirectories\File.txt", foReadWrite)
IF FileID <> -1 THEN
	// Write a line to this file
	ResWrite = fWriteLine(FileID, "Meeting report")
	IF ResWrite = False THEN
		...
	END
END

// Open an external file
MyTextFile is DiskFile
ResWrite is boolean
IF fOpen(MyTextFile, "C:\MyDirectories\File.txt", foReadWrite) = True THEN
	// Write a line to this file
	ResWrite = fWriteLine(MyTextFile, "Meeting report")
	IF ResWrite = False THEN
		...
	END
END

Sintaxis

Writing a line to an external file Ocultar los detalles

<Result> = fWriteLine(<File used> , <Line to write>)

<Result>: Boolean

True if the write operation was performed to the specified file,
False if an error occurs. To get more details on the error, use ErrorInfo with the errMessage constant.

<File used>: Integer or DiskFile variable

Identifier of the file to use, defined by fOpen or fCreate.
Name of the DiskFile variable initialized with fOpen or fCreate.
Not available.
This parameter must be a variant.

<Line to write>: Character string

Line to be written to the file (up to 2GB).

Writing a fixed-length line to an external file (speeds up the write operation) Ocultar los detalles

<Result> = fWriteLine(<File used> , <Address of line to write> , <Size to write>)

<Result>: Boolean

True if the write operation was performed to the specified file,
False if an error occurs. To get more details on the error, use ErrorInfo with the errMessage constant.

<File used>: Integer or DiskFile variable

Identifier of the file to use, defined by fOpen or fCreate.
Name of the DiskFile variable initialized with fOpen or fCreate.

<Address of line to write>: Address

Address of the line to be written to the file.

<Size to write>: Integer

Size in bytes (characters) of the line that must be written (up to 2GB).
This parameter must be less than or equal to the real size of the wine written to the external file. For example, if the size of the line to write is equal to 100 bytes, <Size to write> must be less than or equal to 100 bytes.
If this parameter is less than the real size of the written line, only the specified number of bytes will be written to the text file. The line will be truncated.

Observaciones

Handling errors

fWriteLine throws an error in the following cases:

the file is not opened,
the file is not accessible in write mode,
the file is locked by another computer or by another application,
no disk space is available.

Attention The function fWriteLine function can only be used on text files. This function does not support the binary 0 (the write operation is stopped).

Operating mode in Windows Vista (and later)

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

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

Programming tip: If you need to manipulate / modify files or directories, without needing administrator privileges, it is advisable:

avoid writing to the Windows directory or to the "Program Files" directory,
use the system directory of the application (returned by SysDir with the srAppDataCommun constant, for example).

Remark: Under Windows Vista (and higher), the virtualization mechanism makes applications Vista-compatible.. If the file is created in a system directory without having sufficient rights, this file will actually be created in another directory (C:\Users\<LOGIN>AppData\Local\VirtualStore\Windows\). In this case, the file cannot be shared between several applications.

Position in the file

When opening a file, the current position corresponds to:

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

This position can be modified by fSeek.

fWriteLine writes the specified elements from the current position. Once fWriteLine has been executed, the current position is set to the last byte written.

ANSI / Unicode management

fWriteLine is used to write:

a Unicode string in a Unicode file.
an Ansi string in an Ansi file.

The file is created or opened with fCreate/fOpen by specifying the file type.

Remarks:

The size to be written to a Unicode file must be multiplied by two compared to an ANSI file.

If an ANSI character string is written to a Unicode file (and vice versa), the conversion is implicitly performed.


	Format of the string passed as parameter	External file in ANSI format (fOpen or fCreate associated with the foAnsi constant)	External file in Unicode format (fOpen or fCreate associated with the foUnicode constant)
fWriteLine function	ANSI	No conversion is required before the write operation	Automatic conversion of the string before the write operation
fWriteLine function	Unicode	Automatic conversion of the string before the write operation	No conversion is required before the write operation

In WINDEV and WEBDEV projects, if the "Use ANSI strings at runtime" option is enabled in the project configuration description, the default opening mode is foAnsi (1st column).

In WINDEV and WEBDEV projects, if the "Use UNICODE strings at runtime" option is enabled in the project configuration description, the default opening mode is foUnicode (second column).

In the WINDEV Mobile projects, regardless of the version and mode, the opening mode used by default is foUnicode (second column).

For more details, see Unicode management

Clasificación Lógica de negocio / UI: Lógica de negocio

Componente: wd300std.dll

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Versión mínima requerida

Versión 9

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Última modificación: 27/03/2025

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