The QFile class is an I/O device that operates on files. More...
#include <qfile.h>
Inherits QIODevice.
QFile is an I/O device for reading and writing binary and text files. A QFile may be used by itself (readBlock and writeBlock) or by more conveniently using QDataStream or QTextStream. Most of its behavior is inherited from QIODevice.
The QFileInfo class holds detailed information about a file, such as access permissions, file dates and file types.
The QDir class manages directories and lists of file names.
See also: QDataStream and QTextStream.
Constructs a QFile with a file name name.
See also: setName().
Constructs a QFile with no name.
Destroys a QFile. Calls close().
[virtual]
Sets the file index to pos. Returns TRUE if successful, otherwise FALSE.
Example:
QFile f( "data.bin" ); f.open( IO_ReadOnly ); // index set to 0 f.at( 100 ); // set index to 100 f.at( f.at()+50 ); // set index to 150 f.at( f.size()-80 ); // set index to 80 before EOF f.close();
See also: size().
Reimplemented from QIODevice.
[virtual]
Returns the file index.
See also: size().
Reimplemented from QIODevice.
[virtual]
Returns TRUE if the end of file has been reached, otherwise FALSE.
See also: size().
Reimplemented from QIODevice.
[virtual]
Closes an open file.
The file is closed even if it was opened with an existing file handle or a file descriptor, except that stdin, stdout and stderr are never closed.
Reimplemented from QIODevice.
[static]
Returns TRUE if the file given by fileName exists, otherwise FALSE.
Returns TRUE if the file exists, otherwise FALSE.
See also: name().
[virtual]
Flushes the file buffer to the disk.
close() also flushes the file buffer.
Reimplemented from QIODevice.
[virtual]
Reads a single byte/character from the file.
Returns the byte/character read, or -1 if the end of the file has been reached.
See also: putch() and ungetch().
Reimplemented from QIODevice.
Returns the file handle of the file.
This is a small positive integer, suitable for use with C library functions such as fdopen() and fcntl(), as well as with QSocketNotifier.
If the file is not open or there is an error, handle() returns -1.
See also: QSocketNotifier.
Returns the name set by setName().
See also: setName() and QFileInfo::fileName().
[virtual]
Opens the file specified by the file name currently set, using the mode m. Returns TRUE if successful, otherwise FALSE.
The mode parameter m must be a combination of the following flags.
IO_Raw
specified raw (unbuffered) file access.
IO_ReadOnly
opens a file in read-only mode.
IO_WriteOnly
opens a file in write-only mode.
IO_ReadWrite
opens a file in read/write mode.
IO_Append
sets the file index to the end of the file.
IO_Truncate
truncates the file.
IO_Translate
enables carriage returns and linefeed translation
for text files under MS-DOS, Window, OS/2 and Macintosh. Cannot be
combined with IO_Raw.
The raw access mode is best when I/O is block-operated using 4kB block size or greater. Buffered access works better when reading small portions of data at a time.
If the file does not exist and IO_WriteOnly
or IO_ReadWrite
is
specified, it is created.
Example:
QFile f1( "/tmp/data.bin" ); QFile f2( "readme.txt" ); f1.open( IO_Raw | IO_ReadWrite | IO_Append ); f2.open( IO_ReadOnly | IO_Translate );
See also: name(), close() and isOpen().
Reimplemented from QIODevice.
Opens a file in the mode m using an existing file handle f. Returns TRUE if successful, otherwise FALSE.
Example:
#include <stdio.h> void printError( const char *msg ) { QFile f; f.open( IO_WriteOnly, stderr ); f.writeBlock( msg, strlen(msg) ); // write to stderr f.close(); }
When a QFile is opened using this function, close() does not actually close the file, only flushes it.
Warning: If f is one of stdin, stdout
or stderr,
you may not
be able to seek. size() is set to INT_MAX
(in limits.h).
See also: close().
Opens a file in the mode m using an existing file descriptor f. Returns TRUE if successful, otherwise FALSE.
When a QFile is opened using this function, close() does not actually close the file, only flushes it.
Warning: If f is one of 0 (stdin), 1 (stdout) or 2 (stderr), you may not
be able to seek. size() is set to INT_MAX
(in limits.h).
See also: close().
[virtual]
Writes the character ch to the file.
Returns ch, or -1 if some error occurred.
See also: getch() and ungetch().
Reimplemented from QIODevice.
[virtual]
Reads at most len bytes from the file into p and returns the number of bytes actually read.
Returns -1 if a serious error occurred.
See also: writeBlock().
Reimplemented from QIODevice.
[virtual]
Reads a line of text.
Reads bytes from the file until end-of-line is reached, or up to maxlen bytes, and returns the number of bytes read. The terminating newline is not stripped.
This function is efficient only for buffered files. Avoid
readLine() for files that have been opened with the IO_Raw
flag.
See also: readBlock() and QTextStream::readLine().
Reimplemented from QIODevice.
Sets the name of the file. The name can include an absolute directory path or it can be a name or a path relative to the current directory.
Do not call this function if the file has already been opened.
Note that if the name is relative QFile does not associate it with the current directory. If you change directory before calling open(), open uses the new current directory.
Example:
QFile f; QDir::setCurrent( "/tmp" ); f.setName( "readme.txt" ); QDir::setCurrent( "/home" ); f.open( IO_ReadOnly ); // opens "/home/readme.txt" under UNIX
Also note that the directory separator '/' works for all operating systems supported by Qt.
See also: name(), QFileInfo and QDir.
[virtual]
Returns the file size.
See also: at().
Reimplemented from QIODevice.
[virtual]
Puts the character ch back into the file and decrements the index if it is not zero.
This function is normally called to "undo" a getch() operation.
Returns ch, or -1 if some error occurred.
See also: getch() and putch().
Reimplemented from QIODevice.
[virtual]
Writes len bytes from p to the file and returns the number of bytes actually written.
Returns -1 if a serious error occurred.
See also: readBlock().
Reimplemented from QIODevice.
This file is part of the Qt toolkit, copyright © 1995-97 Troll Tech, all rights reserved.
It was generated from the following files: