Chapter 6 Function Descriptions

FMOpen

MgErr FMOpen(fdp, path, openMode, denyMode);

Purpose

Opens a file with the name and location specified by path for writing and reading, as specified by openMode.

You can use denyMode to control concurrent access to the file from within LabVIEW.

If the function opens the file, the resulting file descriptor is stored in the address referred to by fdp. If an error occurs, the function stores 0 in the address referred to by fdp and returns an error.

Note Before you call this function, make sure that you understand how to use the fdp parameter. Refer to the Pointers as Parameters section in Chapter 3, CINs, for more information about using this parameter.

Parameters

Name	Type	Description
fdp	File *	Address at which FMOpen stores the file
		descriptor for the new file. If FMOpen fails,
		it stores 0 in the address fdp. Refer to the
		Pointers as Parameters section in Chapter 3,
		CINs, for more information about using this
		parameter.
path	Path	Path of the file you want to create.

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				Chapter 6 Function Descriptions
Name		Type		Description
openMode	int32		Access mode to use in opening the file.
			The following values are defined in the file
			extcode.h:
			•	openReadOnly—Open for
				reading.
			•	openWriteOnly—Open for
				writing; file is not truncated (data is
				not removed). In Macintosh, this
				mode provides true write-only
				access to files. In Windows or
				UNIX, LabVIEW I/O functions are
				built in the C standard I/O library,
				with which you have write-only
				access to a file only if you are
				truncating the file or making the
				access append-only. Therefore, this
				mode actually allows both read and
				write access to files in Windows or
				UNIX.
			• openReadWrite— Open for both
				reading and writing.
			•	openWriteOnlyTruncate— Open
				for writing; truncates the file.
denyMode	int32		Mode that determines what level of
			concurrent access to the file is allowed.
			The following values are defined in the file
			extcode.h:
			•	denyReadWrite—Prevents others
				from reading from and writing to
				the file while it is open.
			•	denyWriteOnly—Prevents others
				from writing to the file only while it
				is open.
			• denyNeither—Allows others to
				read from and write to the file while
				it is open.

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File is already open for writing. This error is returned only in Macintosh and Solaris. Windows returns fIOErr when the file is already open for writing.

File not found.

Too many files are open. Unspecified I/O error.

A bad argument was passed to the function. Verify the path.

Chapter 6 Function Descriptions

Return Value

mgErr, which can contain the following errors: mgArgErr

fIsOpen

fNotFound fTMFOpen fIOErr

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Chapter 6 Function Descriptions

FMove

MgErr FMove(oldPath, newPath);

Purpose

Moves a file or renames it if the new path indicates the file is to remain in the same directory.

Parameters

Name	Type	Description
oldPath	Path	Path of the file or directory you want to
		move.
newPath	Path	Path, including the name of the file or
		directory, where you want to move the file or
		directory.

Return Value

mgErr, which can contain the following errors:

mgArgErr	A bad argument was passed to the function. Verify the path.
fNotFound	File not found.
fNoPerm	Access was denied; the file, directory, or disk is locked or
	protected.
fDiskFull	Disk is full.
fDupPath	The new file already exists.
fIsOpen	The original file is open for writing.
fTMFOpen	Too many files are open.
mFullErr	Insufficient memory.
fIOErr	Unspecified I/O error.

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