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< td align = "right" valign = "center" > < img src = "logo32.png" align = "right" width = "64" height = "32" border = "0" > < / td > < / tr > < / table > < h1 align = center > TQIODevice Class Reference< / h1 >
< p > The TQIODevice class is the base class of I/O devices.
< a href = "#details" > More...< / a >
< p > All the functions in this class are < a href = "threads.html#reentrant" > reentrant< / a > when TQt is built with thread support.< / p >
< p > < tt > #include < < a href = "qiodevice-h.html" > ntqiodevice.h< / a > > < / tt >
< p > Inherited by < a href = "ntqbuffer.html" > TQBuffer< / a > , < a href = "ntqfile.html" > TQFile< / a > , < a href = "ntqsocket.html" > TQSocket< / a > , and < a href = "ntqsocketdevice.html" > TQSocketDevice< / a > .
< p > < a href = "qiodevice-members.html" > List of all member functions.< / a >
< h2 > Public Members< / h2 >
< ul >
< li class = fn > typedef TQ_ULONG < a href = "#Offset" > < b > Offset< / b > < / a > < / li >
< li class = fn > < a href = "#TQIODevice" > < b > TQIODevice< / b > < / a > ()< / li >
< li class = fn > virtual < a href = "#~TQIODevice" > < b > ~TQIODevice< / b > < / a > ()< / li >
< li class = fn > int < a href = "#flags" > < b > flags< / b > < / a > () const< / li >
< li class = fn > int < a href = "#mode" > < b > mode< / b > < / a > () const< / li >
< li class = fn > int < a href = "#state" > < b > state< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isDirectAccess" > < b > isDirectAccess< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isSequentialAccess" > < b > isSequentialAccess< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isCombinedAccess" > < b > isCombinedAccess< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isBuffered" > < b > isBuffered< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isRaw" > < b > isRaw< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isSynchronous" > < b > isSynchronous< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isAsynchronous" > < b > isAsynchronous< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isTranslated" > < b > isTranslated< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isReadable" > < b > isReadable< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isWritable" > < b > isWritable< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isReadWrite" > < b > isReadWrite< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isInactive" > < b > isInactive< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#isOpen" > < b > isOpen< / b > < / a > () const< / li >
< li class = fn > int < a href = "#status" > < b > status< / b > < / a > () const< / li >
< li class = fn > void < a href = "#resetStatus" > < b > resetStatus< / b > < / a > ()< / li >
< li class = fn > virtual bool < a href = "#open" > < b > open< / b > < / a > ( int mode ) = 0< / li >
< li class = fn > virtual void < a href = "#close" > < b > close< / b > < / a > () = 0< / li >
< li class = fn > virtual void < a href = "#flush" > < b > flush< / b > < / a > () = 0< / li >
< li class = fn > virtual Offset < a href = "#size" > < b > size< / b > < / a > () const = 0< / li >
< li class = fn > virtual Offset < a href = "#at" > < b > at< / b > < / a > () const< / li >
< li class = fn > virtual bool < a href = "#at-2" > < b > at< / b > < / a > ( Offset pos )< / li >
< li class = fn > virtual bool < a href = "#atEnd" > < b > atEnd< / b > < / a > () const< / li >
< li class = fn > bool < a href = "#reset" > < b > reset< / b > < / a > ()< / li >
< li class = fn > virtual TQ_LONG < a href = "#readBlock" > < b > readBlock< / b > < / a > ( char * data, TQ_ULONG maxlen ) = 0< / li >
< li class = fn > virtual TQ_LONG < a href = "#writeBlock" > < b > writeBlock< / b > < / a > ( const char * data, TQ_ULONG len ) = 0< / li >
< li class = fn > virtual TQ_LONG < a href = "#readLine" > < b > readLine< / b > < / a > ( char * data, TQ_ULONG maxlen )< / li >
< li class = fn > TQ_LONG < a href = "#writeBlock-2" > < b > writeBlock< / b > < / a > ( const TQByteArray & data )< / li >
< li class = fn > virtual TQByteArray < a href = "#readAll" > < b > readAll< / b > < / a > ()< / li >
< li class = fn > virtual int < a href = "#getch" > < b > getch< / b > < / a > () = 0< / li >
< li class = fn > virtual int < a href = "#putch" > < b > putch< / b > < / a > ( int ch ) = 0< / li >
< li class = fn > virtual int < a href = "#ungetch" > < b > ungetch< / b > < / a > ( int ch ) = 0< / li >
< / ul >
< h2 > Protected Members< / h2 >
< ul >
< li class = fn > void < a href = "#setFlags" > < b > setFlags< / b > < / a > ( int flags )< / li >
< li class = fn > void < a href = "#setType" > < b > setType< / b > < / a > ( int type )< / li >
< li class = fn > void < a href = "#setMode" > < b > setMode< / b > < / a > ( int mode )< / li >
< li class = fn > void < a href = "#setState" > < b > setState< / b > < / a > ( int state )< / li >
< li class = fn > void < a href = "#setStatus" > < b > setStatus< / b > < / a > ( int s )< / li >
< / ul >
< hr > < a name = "details" > < / a > < h2 > Detailed Description< / h2 >
< p > The TQIODevice class is the base class of I/O devices.
< p >
< p > An I/O device represents a medium that one can read bytes from
and/or write bytes to. The TQIODevice class is the abstract
superclass of all such devices; classes such as < a href = "ntqfile.html" > TQFile< / a > , < a href = "ntqbuffer.html" > TQBuffer< / a > and
< a href = "ntqsocket.html" > TQSocket< / a > inherit TQIODevice and implement virtual functions such as
write() appropriately.
< p > Although applications sometimes use TQIODevice directly, it is
usually better to use < a href = "ntqtextstream.html" > TQTextStream< / a > and < a href = "ntqdatastream.html" > TQDataStream< / a > , which provide
stream operations on any TQIODevice subclass. TQTextStream provides
text-oriented stream functionality (for human-readable ASCII
files, for example), whereas TQDataStream deals with binary data in
a totally platform-independent manner.
< p > The public member functions in TQIODevice roughly fall into two
groups: the action functions and the state access functions. The
most important action functions are:
< p > < ul >
< p > < li > < a href = "#open" > open< / a > () opens a device for reading and/or writing, depending on
the mode argument.
< p > < li > < a href = "#close" > close< / a > () closes the device and tidies up (e.g. flushes buffered
data)
< p > < li > < a href = "#readBlock" > readBlock< / a > () reads a block of data from the device.
< p > < li > < a href = "#writeBlock" > writeBlock< / a > () writes a block of data to the device.
< p > < li > < a href = "#readLine" > readLine< / a > () reads a line (of text, usually) from the device.
< p > < li > < a href = "#flush" > flush< / a > () ensures that all buffered data are written to the real device.
< p > < / ul >
< p > There are also some other, less used, action functions:
< p > < ul >
< p > < li > < a href = "#getch" > getch< / a > () reads a single character.
< p > < li > < a href = "#ungetch" > ungetch< / a > () forgets the last call to getch(), if possible.
< p > < li > < a href = "#putch" > putch< / a > () writes a single character.
< p > < li > < a href = "#size" > size< / a > () returns the size of the device, if there is one.
< p > < li > < a href = "#at" > at< / a > () returns the current read/write pointer's position, if there
is one for this device, or it moves the pointer if given an offset.
< p > < li > < a href = "#atEnd" > atEnd< / a > () indicates whether there is more to read, if this is
meaningful for this device.
< p > < li > < a href = "#reset" > reset< / a > () moves the read/write pointer to the start of the
device, if that is possible for this device.
< p > < / ul >
< p > The state access are all "get" functions. The TQIODevice subclass
calls < a href = "#setState" > setState< / a > () to update the state, and simple access functions
tell the user of the device what the device's state is. Here are
the settings, and their associated access functions:
< p > < ul >
< p > < li > Access type. Some devices are direct access (it is possible
to read/write anywhere), whereas others are sequential. TQIODevice
provides the access functions (< a href = "#isDirectAccess" > isDirectAccess< / a > (),
< a href = "#isSequentialAccess" > isSequentialAccess< / a > (), and < a href = "#isCombinedAccess" > isCombinedAccess< / a > ()) to tell users what a
given I/O device supports.
< p > < li > Buffering. Some devices are accessed in raw mode, whereas
others are buffered. Buffering usually provides greater
efficiency, particularly for small read/write operations.
< a href = "#isBuffered" > isBuffered< / a > () tells the user whether a given device is buffered.
(This can often be set by the application in the call to < a href = "#open" > open< / a > ().)
< p > < li > Synchronicity. Synchronous devices work immediately (for
example, files). When you read from a file, the file delivers its
data straight away. Other kinds of device, such as a socket
connected to a HTTP server, may not deliver the data until seconds
after you ask to read it. < a href = "#isSynchronous" > isSynchronous< / a > () and < a href = "#isAsynchronous" > isAsynchronous< / a > ()
tell the user how this device operates.
< p > < li > CR/LF translation. For simplicity, applications often like to
see just a single CR/LF style, and TQIODevice subclasses can
provide this. < a href = "#isTranslated" > isTranslated< / a > () returns TRUE if this object
translates CR/LF to just LF. (This can often be set by the
application in the call to open().)
< p > < li > Permissions. Some files cannot be written. For example,
< a href = "#isReadable" > isReadable< / a > (), < a href = "#isWritable" > isWritable< / a > () and < a href = "#isReadWrite" > isReadWrite< / a > () tell the application
whether it can read from and write to a given device. (This can
often be set by the application in the call to < a href = "#open" > open< / a > ().)
< p > < li > Finally, < a href = "#isOpen" > isOpen< / a > () returns TRUE if the device is open, i.e.
after an open() call.
< p > < / ul >
< p > TQIODevice provides numerous pure virtual functions that you need
to implement when subclassing it. Here is a skeleton subclass with
all the members you are sure to need and some that you will
probably need:
< p > < pre >
class MyDevice : public TQIODevice
{
public:
MyDevice();
~MyDevice();
bool open( int mode );
void close();
void flush();
uint size() const;
int at() const; // non-pure virtual
bool at( int ); // non-pure virtual
bool atEnd() const; // non-pure virtual
int readBlock( char *data, uint maxlen );
int writeBlock( const char *data, uint len );
int readLine( char *data, uint maxlen );
int getch();
int putch( int );
int ungetch( int );
};
< / pre >
< p > The three non-pure virtual functions need not be reimplemented for
sequential devices.
< p > < p > See also < a href = "ntqdatastream.html" > TQDataStream< / a > , < a href = "ntqtextstream.html" > TQTextStream< / a > , and < a href = "io.html" > Input/Output and Networking< / a > .
< hr > < h2 > Member Type Documentation< / h2 >
< h3 class = fn > < a name = "Offset" > < / a > TQIODevice::Offset< / h3 >
< p > The offset within the device.
< hr > < h2 > Member Function Documentation< / h2 >
< h3 class = fn > < a name = "TQIODevice" > < / a > TQIODevice::TQIODevice ()
< / h3 >
Constructs an I/O device.
< h3 class = fn > < a name = "~TQIODevice" > < / a > TQIODevice::~TQIODevice ()< tt > [virtual]< / tt >
< / h3 >
Destroys the I/O device.
< h3 class = fn > < a href = "ntqiodevice.html#Offset" > Offset< / a > < a name = "at" > < / a > TQIODevice::at () const< tt > [virtual]< / tt >
< / h3 >
Virtual function that returns the current I/O device position.
< p > This is the position of the data read/write head of the I/O
device.
< p > < p > See also < a href = "#size" > size< / a > ().
< p > Example: < a href = "distributor-example.html#x2666" > distributor/distributor.ui.h< / a > .
< p > Reimplemented in < a href = "ntqsocket.html#at" > TQSocket< / a > .
< h3 class = fn > bool < a name = "at-2" > < / a > TQIODevice::at ( < a href = "ntqiodevice.html#Offset" > Offset< / a > pos )< tt > [virtual]< / tt >
< / h3 >
Virtual function that sets the I/O device position to < em > pos< / em > .
Returns TRUE if the position was successfully set, i.e. < em > pos< / em > is
within range and the seek was successful; otherwise returns FALSE.
< p > < p > See also < a href = "#size" > size< / a > ().
< p > Reimplemented in < a href = "ntqsocket.html#at-2" > TQSocket< / a > .
< h3 class = fn > bool < a name = "atEnd" > < / a > TQIODevice::atEnd () const< tt > [virtual]< / tt >
< / h3 >
Virtual function that returns TRUE if the I/O device position is
at the end of the input; otherwise returns FALSE.
< p > Reimplemented in < a href = "ntqfile.html#atEnd" > TQFile< / a > and < a href = "ntqsocket.html#atEnd" > TQSocket< / a > .
< h3 class = fn > void < a name = "close" > < / a > TQIODevice::close ()< tt > [pure virtual]< / tt >
< / h3 >
< p > Closes the I/O device.
< p > This virtual function must be reimplemented by all subclasses.
< p > < p > See also < a href = "#open" > open< / a > ().
< p > Example: < a href = "grapher-nsplugin-example.html#x2742" > grapher/grapher.cpp< / a > .
< p > Reimplemented in < a href = "ntqfile.html#close" > TQFile< / a > and < a href = "ntqsocket.html#close" > TQSocket< / a > .
< h3 class = fn > int < a name = "flags" > < / a > TQIODevice::flags () const
< / h3 >
< p > Returns the current I/O device flags setting.
< p > Flags consists of mode flags and state flags.
< p > < p > See also < a href = "#mode" > mode< / a > () and < a href = "#state" > state< / a > ().
< h3 class = fn > void < a name = "flush" > < / a > TQIODevice::flush ()< tt > [pure virtual]< / tt >
< / h3 >
< p > Flushes an open I/O device.
< p > This virtual function must be reimplemented by all subclasses.
< p > Reimplemented in < a href = "ntqfile.html#flush" > TQFile< / a > and < a href = "ntqsocket.html#flush" > TQSocket< / a > .
< h3 class = fn > int < a name = "getch" > < / a > TQIODevice::getch ()< tt > [pure virtual]< / tt >
< / h3 >
< p > Reads a single byte/character from the I/O device.
< p > Returns the byte/character read, or -1 if the end of the I/O
device has been reached.
< p > This virtual function must be reimplemented by all subclasses.
< p > < p > See also < a href = "#putch" > putch< / a > () and < a href = "#ungetch" > ungetch< / a > ().
< p > Reimplemented in < a href = "ntqfile.html#getch" > TQFile< / a > and < a href = "ntqsocket.html#getch" > TQSocket< / a > .
< h3 class = fn > bool < a name = "isAsynchronous" > < / a > TQIODevice::isAsynchronous () const
< / h3 >
< p > Returns TRUE if the device is an asynchronous device; otherwise
returns FALSE, i.e. if the device is a synchronous device.
< p > This mode is currently not in use.
< p > < p > See also < a href = "#isSynchronous" > isSynchronous< / a > ().
< h3 class = fn > bool < a name = "isBuffered" > < / a > TQIODevice::isBuffered () const
< / h3 >
< p > Returns TRUE if the I/O device is a buffered device; otherwise
returns FALSE, i.e. the device is a raw device.
< p > < p > See also < a href = "#isRaw" > isRaw< / a > ().
< h3 class = fn > bool < a name = "isCombinedAccess" > < / a > TQIODevice::isCombinedAccess () const
< / h3 >
< p > Returns TRUE if the I/O device is a combined access (both direct
and sequential) device; otherwise returns FALSE.
< p > This access method is currently not in use.
< h3 class = fn > bool < a name = "isDirectAccess" > < / a > TQIODevice::isDirectAccess () const
< / h3 >
< p > 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.
< p > < p > See also < a href = "#isSequentialAccess" > isSequentialAccess< / a > ().
< h3 class = fn > bool < a name = "isInactive" > < / a > TQIODevice::isInactive () const
< / h3 >
< p > Returns TRUE if the I/O device state is 0, i.e. the device is not
open; otherwise returns FALSE.
< p > < p > See also < a href = "#isOpen" > isOpen< / a > ().
< h3 class = fn > bool < a name = "isOpen" > < / a > TQIODevice::isOpen () const
< / h3 >
< p > Returns TRUE if the I/O device has been opened; otherwise returns
FALSE.
< p > < p > See also < a href = "#isInactive" > isInactive< / a > ().
< p > Example: < a href = "networkprotocol-example.html#x670" > network/networkprotocol/nntp.cpp< / a > .
< h3 class = fn > bool < a name = "isRaw" > < / a > TQIODevice::isRaw () const
< / h3 >
< p > Returns TRUE if the device is a raw device; otherwise returns
FALSE, i.e. if the device is a buffered device.
< p > < p > See also < a href = "#isBuffered" > isBuffered< / a > ().
< h3 class = fn > bool < a name = "isReadWrite" > < / a > TQIODevice::isReadWrite () const
< / h3 >
< p > Returns TRUE if the I/O device was opened using < a href = "ntqfile.html#open" > IO_ReadWrite< / a >
mode; otherwise returns FALSE.
< p > < p > See also < a href = "#isReadable" > isReadable< / a > () and < a href = "#isWritable" > isWritable< / a > ().
< h3 class = fn > bool < a name = "isReadable" > < / a > TQIODevice::isReadable () const
< / h3 >
< p > Returns TRUE if the I/O device was opened using < a href = "ntqfile.html#open" > IO_ReadOnly< / a > or
< a href = "ntqfile.html#open" > IO_ReadWrite< / a > mode; otherwise returns FALSE.
< p > < p > See also < a href = "#isWritable" > isWritable< / a > () and < a href = "#isReadWrite" > isReadWrite< / a > ().
< h3 class = fn > bool < a name = "isSequentialAccess" > < / a > TQIODevice::isSequentialAccess () const
< / h3 >
< p > Returns TRUE if the device is a sequential access device;
otherwise returns FALSE, i.e. if the device is a direct access
device.
< p > Operations involving < a href = "#size" > size< / a > () and < a href = "#at" > at< / a > (int) are not valid on
sequential devices.
< p > < p > See also < a href = "#isDirectAccess" > isDirectAccess< / a > ().
< h3 class = fn > bool < a name = "isSynchronous" > < / a > TQIODevice::isSynchronous () const
< / h3 >
< p > Returns TRUE if the I/O device is a synchronous device; otherwise
returns FALSE, i.e. the device is an asynchronous device.
< p > < p > See also < a href = "#isAsynchronous" > isAsynchronous< / a > ().
< h3 class = fn > bool < a name = "isTranslated" > < / a > TQIODevice::isTranslated () const
< / h3 >
< p > Returns TRUE if the I/O device translates carriage-return and
linefeed characters; otherwise returns FALSE.
< p > A < a href = "ntqfile.html" > TQFile< / a > is translated if it is opened with the < a href = "ntqfile.html#open" > IO_Translate< / a >
mode flag.
< h3 class = fn > bool < a name = "isWritable" > < / a > TQIODevice::isWritable () const
< / h3 >
< p > Returns TRUE if the I/O device was opened using < a href = "ntqfile.html#open" > IO_WriteOnly< / a > or
< a href = "ntqfile.html#open" > IO_ReadWrite< / a > mode; otherwise returns FALSE.
< p > < p > See also < a href = "#isReadable" > isReadable< / a > () and < a href = "#isReadWrite" > isReadWrite< / a > ().
< h3 class = fn > int < a name = "mode" > < / a > TQIODevice::mode () const
< / h3 >
< p > Returns bits OR'ed together that specify the current operation
mode.
< p > These are the flags that were given to the < a href = "#open" > open< / a > () function.
< p > The flags are < a href = "ntqfile.html#open" > IO_ReadOnly< / a > , < a href = "ntqfile.html#open" > IO_WriteOnly< / a > , < a href = "ntqfile.html#open" > IO_ReadWrite< / a > ,
< a href = "ntqfile.html#open" > IO_Append< / a > , < a href = "ntqfile.html#open" > IO_Truncate< / a > and < a href = "ntqfile.html#open" > IO_Translate< / a > .
< h3 class = fn > bool < a name = "open" > < / a > TQIODevice::open ( int mode )< tt > [pure virtual]< / tt >
< / h3 >
< p > Opens the I/O device using the specified < em > mode< / em > . Returns TRUE if
the device was successfully opened; otherwise returns FALSE.
< p > The mode parameter < em > mode< / em > must be an OR'ed combination of the
following flags.
< center > < table cellpadding = "4" cellspacing = "2" border = "0" >
< tr bgcolor = "#a2c511" > < th valign = "top" > Mode flags < th valign = "top" > Meaning
< tr bgcolor = "#f0f0f0" > < td valign = "top" > < a href = "ntqfile.html#open" > IO_Raw< / a > < td valign = "top" > specifies raw (unbuffered) file access.
< tr bgcolor = "#d0d0d0" > < td valign = "top" > < a href = "ntqfile.html#open" > IO_ReadOnly< / a > < td valign = "top" > opens a file in read-only mode.
< tr bgcolor = "#f0f0f0" > < td valign = "top" > < a href = "ntqfile.html#open" > IO_WriteOnly< / a > < td valign = "top" > opens a file in write-only mode.
< tr bgcolor = "#d0d0d0" > < td valign = "top" > < a href = "ntqfile.html#open" > IO_ReadWrite< / a > < td valign = "top" > opens a file in read/write mode.
< tr bgcolor = "#f0f0f0" > < td valign = "top" > < a href = "ntqfile.html#open" > IO_Append< / a > < td valign = "top" > sets the file index to the end of the file.
< tr bgcolor = "#d0d0d0" > < td valign = "top" > < a href = "ntqfile.html#open" > IO_Truncate< / a > < td valign = "top" > truncates the file.
< tr bgcolor = "#f0f0f0" > < td valign = "top" > < a href = "ntqfile.html#open" > IO_Translate< / a > < td valign = "top" > 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 < a href = "ntqfile.html#open" > IO_Raw< / a > .
< / table > < / center >
< p > This virtual function must be reimplemented by all subclasses.
< p > < p > See also < a href = "#close" > close< / a > ().
< p > Example: < a href = "grapher-nsplugin-example.html#x2743" > grapher/grapher.cpp< / a > .
< p > Reimplemented in < a href = "ntqfile.html#open" > TQFile< / a > and < a href = "ntqsocket.html#open" > TQSocket< / a > .
< h3 class = fn > int < a name = "putch" > < / a > TQIODevice::putch ( int ch )< tt > [pure virtual]< / tt >
< / h3 >
< p > Writes the character < em > ch< / em > to the I/O device.
< p > Returns < em > ch< / em > , or -1 if an error occurred.
< p > This virtual function must be reimplemented by all subclasses.
< p > < p > See also < a href = "#getch" > getch< / a > () and < a href = "#ungetch" > ungetch< / a > ().
< p > Example: < a href = "grapher-nsplugin-example.html#x2744" > grapher/grapher.cpp< / a > .
< p > Reimplemented in < a href = "ntqfile.html#putch" > TQFile< / a > and < a href = "ntqsocket.html#putch" > TQSocket< / a > .
< h3 class = fn > < a href = "qbytearray.html" > TQByteArray< / a > < a name = "readAll" > < / a > TQIODevice::readAll ()< tt > [virtual]< / tt >
< / h3 >
This convenience function returns all of the remaining data in the
device.
< h3 class = fn > TQ_LONG < a name = "readBlock" > < / a > TQIODevice::readBlock ( char * data, TQ_ULONG maxlen )< tt > [pure virtual]< / tt >
< / h3 >
< p > Reads at most < em > maxlen< / em > bytes from the I/O device into < em > data< / em > and
returns the number of bytes actually read.
< p > This function should return -1 if a fatal error occurs and should
return 0 if there are no bytes to read.
< p > The device must be opened for reading, and < em > data< / em > must not be 0.
< p > This virtual function must be reimplemented by all subclasses.
< p > < p > See also < a href = "#writeBlock" > writeBlock< / a > (), < a href = "#isOpen" > isOpen< / a > (), and < a href = "#isReadable" > isReadable< / a > ().
< p > Example: < a href = "distributor-example.html#x2667" > distributor/distributor.ui.h< / a > .
< p > Reimplemented in < a href = "ntqsocket.html#readBlock" > TQSocket< / a > and < a href = "ntqsocketdevice.html#readBlock" > TQSocketDevice< / a > .
< h3 class = fn > TQ_LONG < a name = "readLine" > < / a > TQIODevice::readLine ( char * data, TQ_ULONG maxlen )< tt > [virtual]< / tt >
< / h3 >
Reads a line of text, (or up to < em > maxlen< / em > bytes if a newline isn't
encountered) plus a terminating '\ 0' into < em > data< / em > . If there is a
newline at the end if the line, it is not stripped.
< p > Returns the number of bytes read including the terminating '\ 0',
or -1 if an error occurred.
< p > This virtual function can be reimplemented much more efficiently
by the most subclasses.
< p > < p > See also < a href = "#readBlock" > readBlock< / a > () and < a href = "ntqtextstream.html#readLine" > TQTextStream::readLine< / a > ().
< p > Reimplemented in < a href = "ntqfile.html#readLine" > TQFile< / a > .
< h3 class = fn > bool < a name = "reset" > < / a > TQIODevice::reset ()
< / h3 >
< p > Sets the device index position to 0.
< p > < p > See also < a href = "#at" > at< / a > ().
< h3 class = fn > void < a name = "resetStatus" > < / a > TQIODevice::resetStatus ()
< / h3 >
< p > Sets the I/O device status to < a href = "ntqiodevice.html#status" > IO_Ok< / a > .
< p > < p > See also < a href = "#status" > status< / a > ().
< h3 class = fn > void < a name = "setFlags" > < / a > TQIODevice::setFlags ( int flags )< tt > [protected]< / tt >
< / h3 >
< p > Used by subclasses to set the device flags to the < em > flags< / em > specified.
< h3 class = fn > void < a name = "setMode" > < / a > TQIODevice::setMode ( int mode )< tt > [protected]< / tt >
< / h3 >
< p > Used by subclasses to set the device mode to the < em > mode< / em > specified.
< h3 class = fn > void < a name = "setState" > < / a > TQIODevice::setState ( int state )< tt > [protected]< / tt >
< / h3 >
< p > Used by subclasses to set the device state to the < em > state< / em > specified.
< h3 class = fn > void < a name = "setStatus" > < / a > TQIODevice::setStatus ( int s )< tt > [protected]< / tt >
< / h3 >
Used by subclasses to set the device status (not state) to < em > s< / em > .
< h3 class = fn > void < a name = "setType" > < / a > TQIODevice::setType ( int type )< tt > [protected]< / tt >
< / h3 >
< p > Used by subclasses to set the device type to the < em > type< / em > specified.
< h3 class = fn > < a href = "ntqiodevice.html#Offset" > Offset< / a > < a name = "size" > < / a > TQIODevice::size () const< tt > [pure virtual]< / tt >
< / h3 >
< p > Virtual function that returns the size of the I/O device.
< p > < p > See also < a href = "#at" > at< / a > ().
< p > Reimplemented in < a href = "ntqfile.html#size" > TQFile< / a > and < a href = "ntqsocket.html#size" > TQSocket< / a > .
< h3 class = fn > int < a name = "state" > < / a > TQIODevice::state () const
< / h3 >
< p > Returns bits OR'ed together that specify the current state.
< p > The flags are: < tt > IO_Open< / tt > .
< p > Subclasses may define additional flags.
< h3 class = fn > int < a name = "status" > < / a > TQIODevice::status () const
< / h3 >
< p > Returns the I/O device status.
< p > The I/O device status returns an error code. If < a href = "#open" > open< / a > () returns
FALSE or < a href = "#readBlock" > readBlock< / a > () or < a href = "#writeBlock" > writeBlock< / a > () return -1, this function can
be called to find out the reason why the operation failed.
< p > <!-- index IO_Ok --> <!-- index IO_ReadError --> <!-- index IO_WriteError --> <!-- index IO_FatalError --> <!-- index IO_OpenError --> <!-- index IO_ConnectError --> <!-- index IO_AbortError --> <!-- index IO_TimeOutError --> <!-- index IO_UnspecifiedError -->
< p > The status codes are:
< center > < table cellpadding = "4" cellspacing = "2" border = "0" >
< tr bgcolor = "#a2c511" > < th valign = "top" > Status code < th valign = "top" > Meaning
< tr bgcolor = "#f0f0f0" > < td valign = "top" > < a href = "ntqiodevice.html#status" > IO_Ok< / a > < td valign = "top" > The operation was successful.
< tr bgcolor = "#d0d0d0" > < td valign = "top" > < a href = "ntqiodevice.html#status" > IO_ReadError< / a > < td valign = "top" > Could not read from the device.
< tr bgcolor = "#f0f0f0" > < td valign = "top" > < a href = "ntqiodevice.html#status" > IO_WriteError< / a > < td valign = "top" > Could not write to the device.
< tr bgcolor = "#d0d0d0" > < td valign = "top" > < a href = "ntqiodevice.html#status" > IO_FatalError< / a > < td valign = "top" > A fatal unrecoverable error occurred.
< tr bgcolor = "#f0f0f0" > < td valign = "top" > < a href = "ntqiodevice.html#status" > IO_OpenError< / a > < td valign = "top" > Could not open the device.
< tr bgcolor = "#d0d0d0" > < td valign = "top" > < a href = "ntqiodevice.html#status" > IO_ConnectError< / a > < td valign = "top" > Could not connect to the device.
< tr bgcolor = "#f0f0f0" > < td valign = "top" > < a href = "ntqiodevice.html#status" > IO_AbortError< / a > < td valign = "top" > The operation was unexpectedly aborted.
< tr bgcolor = "#d0d0d0" > < td valign = "top" > < a href = "ntqiodevice.html#status" > IO_TimeOutError< / a > < td valign = "top" > The operation timed out.
< tr bgcolor = "#f0f0f0" > < td valign = "top" > < a href = "ntqiodevice.html#status" > IO_UnspecifiedError< / a > < td valign = "top" > An unspecified error happened on close.
< / table > < / center >
< p > < p > See also < a href = "#resetStatus" > resetStatus< / a > ().
< h3 class = fn > int < a name = "ungetch" > < / a > TQIODevice::ungetch ( int ch )< tt > [pure virtual]< / tt >
< / h3 >
< p > Puts the character < em > ch< / em > back into the I/O device and decrements
the index position if it is not zero.
< p > This function is normally called to "undo" a < a href = "#getch" > getch< / a > () operation.
< p > Returns < em > ch< / em > , or -1 if an error occurred.
< p > This virtual function must be reimplemented by all subclasses.
< p > < p > See also < a href = "#getch" > getch< / a > () and < a href = "#putch" > putch< / a > ().
< p > Reimplemented in < a href = "ntqfile.html#ungetch" > TQFile< / a > and < a href = "ntqsocket.html#ungetch" > TQSocket< / a > .
< h3 class = fn > TQ_LONG < a name = "writeBlock" > < / a > TQIODevice::writeBlock ( const char * data, TQ_ULONG len )< tt > [pure virtual]< / tt >
< / h3 >
< p > Writes < em > len< / em > bytes from < em > data< / em > to the I/O device and returns the
number of bytes actually written.
< p > This function should return -1 if a fatal error occurs.
< p > This virtual function must be reimplemented by all subclasses.
< p > < p > See also < a href = "#readBlock" > readBlock< / a > ().
< p > Example: < a href = "distributor-example.html#x2668" > distributor/distributor.ui.h< / a > .
< p > Reimplemented in < a href = "ntqbuffer.html#writeBlock" > TQBuffer< / a > , < a href = "ntqsocket.html#writeBlock" > TQSocket< / a > , and < a href = "ntqsocketdevice.html#writeBlock" > TQSocketDevice< / a > .
< h3 class = fn > TQ_LONG < a name = "writeBlock-2" > < / a > TQIODevice::writeBlock ( const < a href = "qbytearray.html" > TQByteArray< / a > & data )
< / h3 >
This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
< p > This convenience function is the same as calling < a href = "#writeBlock" > writeBlock< / a > (
data.data(), data.< a href = "#size" > size< / a > () ).
<!-- eof -->
< hr > < p >
This file is part of the < a href = "index.html" > TQt toolkit< / a > .
Copyright © 1995-2007
< a href = "http://www.trolltech.com/" > Trolltech< / a > . All Rights Reserved.< p > < address > < hr > < div align = center >
< table width = 100% cellspacing = 0 border = 0 > < tr >
< td > Copyright © 2007
< a href = "troll.html" > Trolltech< / a > < td align = center > < a href = "trademarks.html" > Trademarks< / a >
< td align = right > < div align = right > TQt 3.3.8< / div >
< / table > < / div > < / address > < / body >
< / html >
