OFFile Class Reference

this class provides a simple C++ encapsulation layer for stdio FILE pointers. More...

List of all members.

Public Member Functions
	OFFile ()
	default constructor, creates an object that is not associated with any file.
	OFFile (FILE *f)
	create object for given stdio FILE
	~OFFile ()
	destructor. Closes file if still open.
OFBool	fopen (const char *filename, const char *modes)
	opens the file whose name is the string pointed to by path and associates a stream with it.
OFBool	fopen (const OFFilename &filename, const char *modes)
	opens the file whose name is a conventional or wide character string pointed to by path and associates.
OFBool	fdopen (int fd, const char *modes)
	associates a stream with the existing file descriptor, fildes.
OFBool	popen (const char *command, const char *modes)
	opens a process by creating a pipe, forking, and invoking the shell.
OFBool	freopen (const char *filename, const char *modes)
	opens the file whose name is the string pointed to by path and associates the stream pointed maintained by this object with it.
OFBool	tmpfile ()
	generates a unique temporary filename.
int	fclose ()
	dissociates the named stream from its underlying file or set of functions.
int	pclose ()
	waits for the associated process (created with popen) to terminate and returns the exit status of the command as returned by wait4.
size_t	fwrite (const void *ptr, size_t size, size_t n)
	writes n elements of data, each size bytes long, to the stream, obtaining them from the location given by ptr.
size_t	fread (void *ptr, size_t size, size_t n)
	reads n elements of data, each size bytes long, from the stream, storing them at the location given by ptr.
int	fflush ()
	forces a write of all user-space buffered data for the given output or update stream via the stream's underlying write function.
int	fgetc ()
	reads the next character from stream and returns it as an unsigned char cast to an int, or EOF on end of file or error.
void	setlinebuf ()
	The three types of buffering available are unbuffered, block buffered, and line buffered.
void	rewind ()
	sets the file position indicator for the stream pointed to by stream to the beginning of the file.
void	clearerr ()
	clears the end-of-file and error indicators for the stream
int	eof () const
	tests the end-of-file indicator for the stream, returning non-zero if it is set.
int	error ()
	tests the error indicator for the stream, returning non-zero if it is set.
int	fileNo ()
	returns the low-level file descriptor associated with the stream.
void	setbuf (char *buf)
	The three types of buffering available are unbuffered, block buffered, and line buffered.
int	setvbuf (char *buf, int modes, size_t n)
	The three types of buffering available are unbuffered, block buffered, and line buffered.
void	setbuffer (char *buf, size_t size)
	The three types of buffering available are unbuffered, block buffered, and line buffered.
int	fputc (int c)
	writes the character c, cast to an unsigned char, to stream.
char *	fgets (char *s, int n)
	reads in at most one less than n characters from stream and stores them into the buffer pointed to by s.
int	fputs (const char *s)
	writes the string s to stream, without its trailing '\0'.
int	ungetc (int c)
	pushes c back to stream, cast to unsigned char, where it is available for subsequent read operations.
int	fseek (offile_off_t off, int whence)
	sets the file position indicator for the stream pointed to by stream.
offile_off_t	ftell ()
	obtains the current value of the file position indicator for the stream pointed to by the stream.
int	fgetpos (offile_fpos_t *pos)
	alternate interface equivalent to ftell, storing the current value of the file offset into the object referenced by pos.
int	fsetpos (offile_fpos_t *pos)
	alternate interface equivalent to fseek (with whence set to SEEK_SET), setting the current value of the file offset from the object referenced by pos.
int	fprintf (const char *format,...)
	print formatted string into stream, see printf(3)
int	vfprintf (const char *format, va_list arg)
	print formatted string into stream, see printf(3)
FILE *	file ()
	return FILE pointer managed by this object.
OFBool	open () const
	return true if this object is currently associated with a stream, false otherwise
offile_errno_t	getLastError () const
	return last error code for this stream
void	getLastErrorString (OFString &s) const
	return string describing last error code for this stream
Private Member Functions
	OFFile (const OFFile &arg)
OFFile &	operator= (const OFFile &arg)
void	storeLastError ()
	store last error code. For now we simply store the content of errno.
Private Attributes
FILE *	file_
	the file maintained by this object
OFBool	popened_
	a flag indicating whether or not this object was created with popen().
offile_errno_t	lasterror_
	the last error code for operations of this stream

---

Detailed Description

this class provides a simple C++ encapsulation layer for stdio FILE pointers.

All stdio functions on files are directly mapped into member functions. The handling of large files (64 bit file systems) is transparent. Instead of type off_t, fseek() and ftell() use offile_off_t which is a 64 bit type if available on the underlying platform. Similarly, getpos() and setpos() use type offile_fpos_t, which is defined appropriately. This class provides both fclose() and pclose(), but these are equivalent - the code always closes pipes with pclose() and files with fclose(). Finally, an abstraction for errno is provided. Error codes should always be retrieves using methods getLastError() and getLastErrorString() which on Unix platforms are based on errno and strerror/strerror_r, but may be based on other mechanisms on platforms where errno does not exist.

---

Constructor & Destructor Documentation

OFFile::OFFile

(

FILE *

f

)

[inline]

create object for given stdio FILE

Parameters:

f	stdio FILE

---

Member Function Documentation

int OFFile::eof

(

)

const [inline]

tests the end-of-file indicator for the stream, returning non-zero if it is set.

The end-of-file indicator can only be cleared by the function clearerr. This method is called eof, not feof, because feof() is a macro on some systems and, therefore, cannot be used as a method name.

Returns:

non-zero if EOF, zero otherwise

int OFFile::error

(

)

[inline]

tests the error indicator for the stream, returning non-zero if it is set.

This method is named error, not ferror, because ferror() is a macro on some systems and, therefore, cannot be used as a method name. The error indicator can only be reset by the clearerr function.

Returns:

non-zero if error flag is set, zero otherwise

int OFFile::fclose

(

)

[inline]

dissociates the named stream from its underlying file or set of functions.

If the stream was being used for output, any buffered data is written first, using fflush. Independent of the return value of this method, any further access (including another call to fclose()) to the stream maintained by this object results in undefined behaviour.

Returns:

0 upon success, EOF otherwise, in which case the error code is set.

OFBool OFFile::fdopen	(	int	fd,
		const char *	modes
	)		[inline]

associates a stream with the existing file descriptor, fildes.

The mode of the stream (one of the values "r", "r+", "w", "w+", "a", "a+") must be compatible with the mode of the file descriptor. The file position indicator of the new stream is set to that belong­ ing to fildes, and the error and end-of-file indicators are cleared. Modes "w" or "w+" do not cause truncation of the file. The file descriptor is not dup'ed, and will be closed when the stream created by fdopen is closed. The result of applying fdopen to a shared memory object is undefined.

Parameters:

fd	file descriptor
modes	"r", "w" or "a" with possible modifiers "+", "b"

Returns:

true if stream was successfully created, false otherwise, in which case the error code is set.

int OFFile::fflush

(

)

[inline]

forces a write of all user-space buffered data for the given output or update stream via the stream's underlying write function.

The open status of the stream is unaffected.

Returns:

0 upon success, EOF otherwise, in which case the error code is set.

int OFFile::fgetc

(

)

[inline]

reads the next character from stream and returns it as an unsigned char cast to an int, or EOF on end of file or error.

Returns:

next character from stream or EOF

int OFFile::fgetpos

(

offile_fpos_t *

pos

)

[inline]

alternate interface equivalent to ftell, storing the current value of the file offset into the object referenced by pos.

On some non-UNIX systems an fpos_t object may be a complex object and these routines may be the only way to portably reposition a text stream.

Parameters:

pos	pointer to offile_fpos_t structure

Returns:

0 upon success, -1 otherwise in which case the error code is set.

char* OFFile::fgets	(	char *	s,
		int	n
	)		[inline]

reads in at most one less than n characters from stream and stores them into the buffer pointed to by s.

Reading stops after an EOF or a newline. If a newline is read, it is stored into the buffer. A '\0' is stored after the last character in the buffer.

Parameters:

s	pointer to buffer of size n
n	buffer size

Returns:

pointer to string

FILE* OFFile::file

(

)

[inline]

return FILE pointer managed by this object.

This allows the user to call some stdio functions that are not encapsulated in this class (but possibly should be).

Returns:

pointer to FILE structure managed by this object

int OFFile::fileNo

(

)

[inline]

returns the low-level file descriptor associated with the stream.

The spelling of this member function is different from stdio fileno() because on some systems (such as MinGW) fileno() is a macro and, therefore, cannot be used as a method name.

Returns:

low-level file descriptor associated with stream

OFBool OFFile::fopen	(	const char *	filename,
		const char *	modes
	)		[inline]

opens the file whose name is the string pointed to by path and associates a stream with it.

Parameters:

filename	path to file
modes	"r", "w" or "a" with possible modifiers "+", "b"

Returns:

true if stream was successfully created, false otherwise, in which case the error code is set.

OFBool OFFile::fopen	(	const OFFilename &	filename,
		const char *	modes
	)		[inline]

opens the file whose name is a conventional or wide character string pointed to by path and associates.

The wide character support is currently Windows-specific.

Parameters:

filename	object containing the filename path to file
modes	"r", "w" or "a" with possible modifiers "+", "b"

Returns:

true if stream was successfully created, false otherwise, in which case the error code is set.

int OFFile::fprintf	(	const char *	format,
			...
	)		[inline]

print formatted string into stream, see printf(3)

Parameters:

format	format string
...	further parameters according to format string

Returns:

number of characters printed

int OFFile::fputc

(

int

c

)

[inline]

writes the character c, cast to an unsigned char, to stream.

Parameters:

c

character

Returns:

the character written as an unsigned char cast to an int or EOF on error

int OFFile::fputs

(

const char *

s

)

[inline]

writes the string s to stream, without its trailing '\0'.

Parameters:

s	string to be written

Returns:

a non-negative number on success, or EOF on error.

size_t OFFile::fread	(	void *	ptr,
		size_t	size,
		size_t	n
	)		[inline]

reads n elements of data, each size bytes long, from the stream, storing them at the location given by ptr.

Returns the number of items successfully read (i.e., not the number of characters). If an error occurs, or the end-of-file is reached, the return value is a short item count (or zero). fread does not distinguish between end-of-file and error, and callers must use feof and ferror to determine which occurred.

Parameters:

ptr	pointer to buffer
size	size of item
n	number of items

Returns:

number of items read

OFBool OFFile::freopen	(	const char *	filename,
		const char *	modes
	)		[inline]

opens the file whose name is the string pointed to by path and associates the stream pointed maintained by this object with it.

The original stream (if it exists) is closed. The mode argument is used just as in the fopen function. The primary use of the freopen function is to change the file associated with a standard text stream (stderr, stdin, or stdout).

Parameters:

filename	path to file
modes	"r", "w" or "a" with possible modifiers "+", "b"

Returns:

true if stream was successfully created, false otherwise, in which case the error code is set.

int OFFile::fseek	(	offile_off_t	off,
		int	whence
	)		[inline]

sets the file position indicator for the stream pointed to by stream.

The new position, measured in bytes, is obtained by adding offset bytes to the position specified by whence. If whence is set to SEEK_SET, SEEK_CUR, or SEEK_END, the offset is relative to the start of the file, the current position indicator, or end-of-file, respectively. A successful call to the fseek function clears the end-of- file indicator for the stream and undoes any effects of the ungetc function on the same stream.

Parameters:

off	offset to seek to
whence	SEEK_SET, SEEK_CUR, or SEEK_END

Returns:

0 upon success, -1 otherwise in which case the error code is set.

int OFFile::fsetpos

(

offile_fpos_t *

pos

)

[inline]

alternate interface equivalent to fseek (with whence set to SEEK_SET), setting the current value of the file offset from the object referenced by pos.

On some non-UNIX systems an fpos_t object may be a complex object and these routines may be the only way to portably reposition a text stream.

Parameters:

pos	pointer to offile_fpos_t structure

Returns:

0 upon success, -1 otherwise in which case the error code is set.

offile_off_t OFFile::ftell

(

)

[inline]

obtains the current value of the file position indicator for the stream pointed to by the stream.

Returns:

current file position

size_t OFFile::fwrite	(	const void *	ptr,
		size_t	size,
		size_t	n
	)		[inline]

writes n elements of data, each size bytes long, to the stream, obtaining them from the location given by ptr.

Returns the number of items successfully written (i.e., not the number of characters). If an error occurs the return value is a short item count (or zero).

Parameters:

ptr	pointer to buffer
size	size of item
n	number of items

Returns:

number of items written

offile_errno_t OFFile::getLastError

(

)

const [inline]

return last error code for this stream

Returns:

last error code for this stream

void OFFile::getLastErrorString

(

OFString &

s

)

const [inline]

return string describing last error code for this stream

Parameters:

s	string describing last error code for this stream returned in this parameter

OFBool OFFile::open

(

)

const [inline]

return true if this object is currently associated with a stream, false otherwise

Returns:

true if this object is currently associated with a stream, false otherwise

int OFFile::pclose

(

)

[inline]

waits for the associated process (created with popen) to terminate and returns the exit status of the command as returned by wait4.

In this implementation, fclose and pclose can be used synonymously.

Returns:

process ID of the child which exited, or -1 on error, in which case the error code is set

OFBool OFFile::popen	(	const char *	command,
		const char *	modes
	)		[inline]

opens a process by creating a pipe, forking, and invoking the shell.

Since a pipe is by definition unidirectional, the type argument may specify only reading or writing, not both; the resulting stream is correspondingly read-only or write-only. If the object was already associated with another file or pipe, that one is closed.

Parameters:

command	shell command line
modes	"r" or "w"

Returns:

true if pipe was successfully created, false otherwise

void OFFile::rewind

(

)

[inline]

sets the file position indicator for the stream pointed to by stream to the beginning of the file.

This is equivalent to fseek(0, SEEK_SET) except that the error indicator for the stream is also cleared.

void OFFile::setbuf

(

char *

buf

)

[inline]

The three types of buffering available are unbuffered, block buffered, and line buffered.

When an output stream is unbuffered, information appears on the destination file or terminal as soon as written; when it is block buffered many characters are saved up and written as a block; when it is line buffered characters are saved up until a newline is output or input is read from any stream attached to a terminal device (typically stdin). Normally all files are block buffered. if a stream refers to a terminal (as stdout normally does) it is line buffered. The standard error stream stderr is always unbuffered by default. This function allows to set the mode of the stream to unbuffered (if buf is NULL) or block buffered.

Parameters:

buf	pointer to buffer of size BUFSIZ as declared in cstdio, or NULL

Returns:

0 upon success, nonzero otherwise, in which case the error code may be set

void OFFile::setbuffer	(	char *	buf,
		size_t	size
	)		[inline]

The three types of buffering available are unbuffered, block buffered, and line buffered.

When an output stream is unbuffered, information appears on the destination file or terminal as soon as written; when it is block buffered many characters are saved up and written as a block; when it is line buffered characters are saved up until a newline is output or input is read from any stream attached to a terminal device (typically stdin). Normally all files are block buffered. if a stream refers to a terminal (as stdout normally does) it is line buffered. The standard error stream stderr is always unbuffered by default. This function allows to set the mode of the stream to unbuffered (if buf is NULL) or block buffered.

Parameters:

buf	pointer to buffer
size	size of buffer, in bytes

Returns:

0 upon success, nonzero otherwise, in which case the error code may be set

void OFFile::setlinebuf

(

)

[inline]

The three types of buffering available are unbuffered, block buffered, and line buffered.

When an output stream is unbuffered, information appears on the destination file or terminal as soon as written; when it is block buffered many characters are saved up and written as a block; when it is line buffered characters are saved up until a newline is output or input is read from any stream attached to a terminal device (typically stdin). Normally all files are block buffered. if a stream refers to a terminal (as stdout normally does) it is line buffered. The standard error stream stderr is always unbuffered by default. this function allows to set the mode of the stream to line buffered.

Returns:

0 upon success, nonzero otherwise, in which case the error code may be set

int OFFile::setvbuf	(	char *	buf,
		int	modes,
		size_t	n
	)		[inline]

The three types of buffering available are unbuffered, block buffered, and line buffered.

When an output stream is unbuffered, information appears on the destination file or terminal as soon as written; when it is block buffered many characters are saved up and written as a block; when it is line buffered characters are saved up until a newline is output or input is read from any stream attached to a terminal device (typically stdin). Normally all files are block buffered. if a stream refers to a terminal (as stdout normally does) it is line buffered. The standard error stream stderr is always unbuffered by default. This function allows to set the stream mode.

Parameters:

buf	pointer to buffer, may be NULL
modes	_IONBF (unbuffered) _IOLBF (line buffered) or _IOFBF (fully buffered)
n	size of buffer, in bytes

Returns:

0 upon success, nonzero otherwise, in which case the error code may be set

OFBool OFFile::tmpfile

(

)

[inline]

generates a unique temporary filename.

The temporary file is then opened in binary read/write (w+b) mode. The file will be automatically deleted when it is closed or the program terminates normally.

Returns:

true if stream was successfully created, false otherwise, in which case the error code is set.

int OFFile::ungetc

(

int

c

)

[inline]

pushes c back to stream, cast to unsigned char, where it is available for subsequent read operations.

Pushed - back characters will be returned in reverse order; only one pushback is guaranteed.

Parameters:

c	character to push back

Returns:

c on success, or EOF on error.

int OFFile::vfprintf	(	const char *	format,
		va_list	arg
	)		[inline]

print formatted string into stream, see printf(3)

Parameters:

format	format string
arg	list of further parameters according to format string

Returns:

number of characters printed

---

The documentation for this class was generated from the following file:

• ofstd/include/dcmtk/ofstd/offile.h