qiodevice.3qt

linux下GUI编程工具qt的在线连接帮助手册

.SH "bool QIODevice::at ( Offset pos )\fC [virtual]\fR"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
Virtual function that sets the I/O device position to \fIpos\fR.
.PP
See also size().
.PP
Reimplemented in QFile and QSocket.
.SH "bool QIODevice::atEnd () const\fC [virtual]\fR"
Virtual function that returns TRUE if the I/O device position is at the end of the input; otherwise returns FALSE.
.PP
Reimplemented in QFile and QSocket.
.SH "void QIODevice::close ()\fC [virtual]\fR"
Closes the I/O device.
.PP
This virtual function must be reimplemented by all subclasses.
.PP
See also open().
.PP
Example: grapher/grapher.cpp.
.PP
Reimplemented in QFile and QSocket.
.SH "int QIODevice::flags () const"
Returns the current I/O device flags setting.
.PP
Flags consists of mode flags and state flags.
.PP
See also mode() and state().
.SH "void QIODevice::flush ()\fC [virtual]\fR"
Flushes an open I/O device.
.PP
This virtual function must be reimplemented by all subclasses.
.PP
Reimplemented in QFile and QSocket.
.SH "int QIODevice::getch ()\fC [virtual]\fR"
Reads a single byte/character from the I/O device.
.PP
Returns the byte/character read, or -1 if the end of the I/O device has been reached.
.PP
This virtual function must be reimplemented by all subclasses.
.PP
See also putch() and ungetch().
.PP
Reimplemented in QFile and QSocket.
.SH "bool QIODevice::isAsynchronous () const"
Returns TRUE if the device is an asynchronous device; otherwise returns FALSE, i.e. if the device is a synchronous device.
.PP
This mode is currently not in use.
.PP
See also isSynchronous().
.SH "bool QIODevice::isBuffered () const"
Returns TRUE if the I/O device is a buffered device; otherwise returns FALSE, i.e. the device is a raw device.
.PP
See also isRaw().
.SH "bool QIODevice::isCombinedAccess () const"
Returns TRUE if the I/O device is a combined access (both direct and sequential) device; otherwise returns FALSE.
.PP
This access method is currently not in use.
.SH "bool QIODevice::isDirectAccess () const"
Returns TRUE if the I/O device is a direct access device; otherwise returns FALSE, i.e. if the device is a sequential access device.
.PP
See also isSequentialAccess().
.SH "bool QIODevice::isInactive () const"
Returns TRUE if the I/O device state is 0, i.e. the device is not open; otherwise returns FALSE.
.PP
See also isOpen().
.SH "bool QIODevice::isOpen () const"
Returns TRUE if the I/O device has been opened; otherwise returns FALSE.
.PP
See also isInactive().
.PP
Example: network/networkprotocol/nntp.cpp.
.SH "bool QIODevice::isRaw () const"
Returns TRUE if the device is a raw device; otherwise returns FALSE, i.e. if the device is a buffered device.
.PP
See also isBuffered().
.SH "bool QIODevice::isReadWrite () const"
Returns TRUE if the I/O device was opened using IO_ReadWrite mode; otherwise returns FALSE.
.PP
See also isReadable() and isWritable().
.SH "bool QIODevice::isReadable () const"
Returns TRUE if the I/O device was opened using IO_ReadOnly or IO_ReadWrite mode; otherwise returns FALSE.
.PP
See also isWritable() and isReadWrite().
.SH "bool QIODevice::isSequentialAccess () const"
Returns TRUE if the device is a sequential access device; otherwise returns FALSE, i.e. if the device is a direct access device.
.PP
Operations involving size() and at(int) are not valid on sequential devices.
.PP
See also isDirectAccess().
.SH "bool QIODevice::isSynchronous () const"
Returns TRUE if the I/O device is a synchronous device; otherwise returns FALSE, i.e. the device is an asynchronous device.
.PP
See also isAsynchronous().
.SH "bool QIODevice::isTranslated () const"
Returns TRUE if the I/O device translates carriage-return and linefeed characters; otherwise returns FALSE.
.PP
A QFile is translated if it is opened with the IO_Translate mode flag.
.SH "bool QIODevice::isWritable () const"
Returns TRUE if the I/O device was opened using IO_WriteOnly or IO_ReadWrite mode; otherwise returns FALSE.
.PP
See also isReadable() and isReadWrite().
.SH "int QIODevice::mode () const"
Returns bits OR'ed together that specify the current operation mode.
.PP
These are the flags that were given to the open() function.
.PP
The flags are IO_ReadOnly, IO_WriteOnly, IO_ReadWrite, IO_Append, IO_Truncate and IO_Translate.
.SH "bool QIODevice::open ( int mode )\fC [virtual]\fR"
Opens the I/O device using the specified \fImode\fR. Returns TRUE if the device was successfully opened; otherwise returns FALSE.
.PP
The mode parameter \fImode\fR must be an OR'ed combination of the following flags.
.TP
IO_Raw specified raw (unbuffered) file access.
.TP
IO_ReadOnly opens a file in read-only mode.
.TP
IO_WriteOnly opens a file in write-only mode.
.TP
IO_ReadWrite opens a file in read/write mode.
.TP
IO_Append sets the file index to the end of the file.
.TP
IO_Truncate truncates the file.
.TP
IO_Translate enables carriage returns and linefeed translation for text files under MS-DOS, Windows and Macintosh. On Unix systems this flag has no effect. Use with caution as it will also transform every linefeed written to the file into a CRLF pair. This is likely to corrupt your file if you write write binary data. Cannot be combined with IO_Raw.
.PP
This virtual function must be reimplemented by all subclasses.
.PP
See also close().
.PP
Example: grapher/grapher.cpp.
.PP
Reimplemented in QFile and QSocket.
.SH "int QIODevice::putch ( int ch )\fC [virtual]\fR"
Writes the character \fIch\fR to the I/O device.
.PP
Returns \fIch\fR, or -1 if an error occurred.
.PP
This virtual function must be reimplemented by all subclasses.
.PP
See also getch() and ungetch().
.PP
Example: grapher/grapher.cpp.
.PP
Reimplemented in QFile and QSocket.
.SH "QByteArray QIODevice::readAll ()\fC [virtual]\fR"
This convenience function returns all of the remaining data in the device.
.SH "Q_LONG QIODevice::readBlock ( char * data, Q_ULONG maxlen )\fC [virtual]\fR"
Reads at most \fImaxlen\fR bytes from the I/O device into \fIdata\fR and returns the number of bytes actually read.
.PP
This virtual function must be reimplemented by all subclasses.
.PP
See also writeBlock().
.PP
Reimplemented in QFile, QSocket and QSocketDevice.
.SH "Q_LONG QIODevice::readLine ( char * data, Q_ULONG maxlen )\fC [virtual]\fR"
Reads a line of text, (or up to \fImaxlen\fR bytes if a newline isn't encountered) plus a terminating \0 into \fIdata\fR. If there is a newline at the end if the line, it is not stripped.
.PP
Returns the number of bytes read including the terminating \0, or -1 in case of error.
.PP
This virtual function can be reimplemented much more efficiently by the most subclasses.
.PP
See also readBlock() and QTextStream::readLine().
.PP
Examples:
.)l network/clientserver/client/client.cpp, network/httpd/httpd.cpp, network/mail/smtp.cpp and network/networkprotocol/nntp.cpp.
.PP
Reimplemented in QFile.
.SH "bool QIODevice::reset ()"
Sets the device index position to 0.
.PP
See also at().
.SH "void QIODevice::resetStatus ()"
Sets the I/O device status to IO_Ok.
.PP
See also status().
.SH "Offset QIODevice::size () const\fC [virtual]\fR"
Virtual function that returns the size of the I/O device.
.PP
See also at().
.PP
Reimplemented in QFile and QSocket.
.SH "int QIODevice::state () const"
Returns bits OR'ed together that specify the current state.
.PP
The flags are: \fCIO_Open\fR.
.PP
Subclasses may define additional flags.
.SH "int QIODevice::status () const"
Returns the I/O device status.
.PP
The I/O device status returns an error code. If open() returns FALSE or readBlock() or writeBlock() return -1, this function can be called to find out the reason why the operation did not succeed.
.PP

.PP
The status codes are:
.TP
IO_Ok - The operation was successful.
.TP
IO_ReadError - Could not read from the device.
.TP
IO_WriteError - Could not write to the device.
.TP
IO_FatalError - A fatal unrecoverable error occurred.
.TP
IO_OpenError - Could not open the device.
.TP
IO_ConnectError - Could not connect to the device.
.TP
IO_AbortError - The operation was unexpectedly aborted.
.TP
IO_TimeOutError - The operation timed out.
.TP
IO_UnspecifiedError - An unspecified error happened on close.
.PP
See also resetStatus().
.SH "int QIODevice::ungetch ( int ch )\fC [virtual]\fR"
Puts the character \fIch\fR back into the I/O device and decrements the index position if it is not zero.
.PP
This function is normally called to "undo" a getch() operation.
.PP
Returns \fIch\fR, or -1 if an error occurred.
.PP
This virtual function must be reimplemented by all subclasses.
.PP
See also getch() and putch().
.PP
Reimplemented in QFile and QSocket.
.SH "Q_LONG QIODevice::writeBlock ( const char * data, Q_ULONG len )\fC [virtual]\fR"
Writes \fIlen\fR bytes from \fIdata\fR to the I/O device and returns the number of bytes actually written.
.PP
This virtual function must be reimplemented by all subclasses.
.PP
See also readBlock().
.PP
Reimplemented in QBuffer, QSocket and QSocketDevice.
.SH "Q_LONG QIODevice::writeBlock ( const QByteArray & data )"
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
.PP
This convenience function is the same as calling
writeBlock( data.data(), data.size() ).

.SH "SEE ALSO"
.BR http://doc.trolltech.com/qiodevice.html
.BR http://www.trolltech.com/faq/tech.html
.SH COPYRIGHT
Copyright 1992-2001 Trolltech AS, http://www.trolltech.com.  See the
license file included in the distribution for a complete license
statement.
.SH AUTHOR
Generated automatically from the source code.
.SH BUGS
If you find a bug in Qt, please report it as described in
.BR http://doc.trolltech.com/bughowto.html .
Good bug reports help us to help you. Thank you.
.P
The definitive Qt documentation is provided in HTML format; it is
located at $QTDIR/doc/html and can be read using Qt Assistant or with
a web browser. This man page is provided as a convenience for those
users who prefer man pages, although this format is not officially
supported by Trolltech. 
.P
If you find errors in this manual page, please report them to
.BR [e-mail] .
Please include the name of the manual page (qiodevice.3qt) and the Qt
version (3.0.0).