QBuffer Class Reference

The QBuffer class is an I/O device that operates on a QByteArray. More...

#include <qbuffer.h>

Inheritance diagram for QBuffer:

Public Member Functions
	QBuffer ()
	QBuffer (QByteArray)
	~QBuffer ()
QByteArray	buffer () const
bool	setBuffer (QByteArray)
bool	open (int)
void	close ()
void	flush ()
uint	size () const
int	at () const
bool	at (int)
int	readBlock (char *p, uint)
int	writeBlock (const char *p, uint)
int	readLine (char *p, uint)
int	getch ()
int	putch (int)
int	ungetch (int)
Public Member Functions inherited from QIODevice
	QIODevice ()
virtual	~QIODevice ()
int	flags () const
int	mode () const
int	state () const
bool	isDirectAccess () const
bool	isSequentialAccess () const
bool	isCombinedAccess () const
bool	isBuffered () const
bool	isRaw () const
bool	isSynchronous () const
bool	isAsynchronous () const
bool	isTranslated () const
bool	isReadable () const
bool	isWritable () const
bool	isReadWrite () const
bool	isInactive () const
bool	isOpen () const
int	status () const
void	resetStatus ()
virtual bool	atEnd () const
bool	reset ()
int	writeBlock (const QByteArray &data)
QByteArray	readAll ()

Protected Attributes
QByteArray	a
Protected Attributes inherited from QIODevice
int	ioIndex

Additional Inherited Members
Protected Member Functions inherited from QIODevice
void	setFlags (int f)
void	setType (int)
void	setMode (int)
void	setState (int)
void	setStatus (int)

Detailed Description

The QBuffer class is an I/O device that operates on a QByteArray.

QBuffer allows reading and writing a memory buffer. It is normally used together with a QTextStream or a QDataStream. QBuffer has an associated QByteArray which holds the buffer data. The size() of the buffer is automatically adjusted as data is written.

The constructor QBuffer(QByteArray) creates a QBuffer with an existing byte array. The byte array can also be set with setBuffer(). Writing to the QBuffer will modify the original byte array, since QByteArray is explicitly shared.

Use open() to open the buffer before use, and to set the mode (read-only,write-only, etc.). close() closes the buffer. The buffer must be closed before reopening or calling setBuffer().

The common way to use QBuffer is through QDataStream or QTextStream which have constructors that take a QBuffer parameter. For convenience, there are also QDataStream and QTextStream constructors that take a QByteArray parameter. These constructors create and open an internal QBuffer.

Note that QTextStream can also operate on a QString (a Unicode string); a QBuffer cannot.

You can also use QBuffer directly through the standard QIODevice functions readBlock(), writeBlock() readLine(), at(), getch(), putch() and ungetch().

See also

QFile, QDataStream, QTextStream, QByteArray, Shared Classes

Constructor & Destructor Documentation

QBuffer() [1/2]

QBuffer::QBuffer

(

)

Constructs an empty buffer.

QBuffer() [2/2]

QBuffer::QBuffer

(

QByteArray

buf

)

Constructs a buffer that operates on buf. If you open the buffer in write mode (IO_WriteOnly or IO_ReadWrite) and write something into the buffer, buf will be modified.

Example:

QCString str = "abc";
QBuffer b( str );
b.open( IO_WriteOnly );
b.at( 3 );                    // position at \0
b.writeBlock( "def", 4 );         // write including \0
b.close();
  // Now, str == "abcdef"

See also

setBuffer()

~QBuffer()

QBuffer::~QBuffer

(

)

Destructs the buffer.

Member Function Documentation

at() [1/2]

int QBuffer::at ( ) const

inlinevirtual

Reimplemented from QIODevice.

at() [2/2]

bool QBuffer::at ( int  pos )

virtual

Reimplemented from QIODevice.

buffer()

QByteArray QBuffer::buffer ( ) const

inline

Returns this buffer's byte array.

See also

setBuffer()

close()

void QBuffer::close ( )

virtual

Closes an open buffer.

See also

open()

Implements QIODevice.

flush()

void QBuffer::flush ( )

virtual

The flush function does nothing for a QBuffer.

Implements QIODevice.

getch()

int QBuffer::getch ( )

virtual

Implements QIODevice.

open()

bool QBuffer::open ( int  m )

virtual

Opens the buffer in the mode m. Returns TRUE if successful, otherwise FALSE. The buffer must be opened before use.

The mode parameter m must be a combination of the following flags.

• IO_ReadOnly opens a buffer in read-only mode.
• IO_WriteOnly opens a buffer in write-only mode.
• IO_ReadWrite opens a buffer in read/write mode.
• IO_Append sets the buffer index to the end of the buffer.
• IO_Truncate truncates the buffer.

See also

close(), isOpen()

Implements QIODevice.

putch()

int QBuffer::putch ( int  ch )

virtual

Writes the character ch into the buffer, overwriting the character at the current index, extending the buffer if necessary.

Returns ch, or -1 if some error occurred.

See also

getch(), ungetch()

Implements QIODevice.

readBlock()

int QBuffer::readBlock ( char *  p, uint  len  )

virtual

Implements QIODevice.

readLine()

int QBuffer::readLine ( char *  p, uint  maxlen  )

virtual

Reimplemented from QIODevice.

setBuffer()

bool QBuffer::setBuffer

(

QByteArray

buf

)

Replaces the buffer's contents with buf.

This may not be done when isOpen() is TRUE.

Note that if you open the buffer in write mode (IO_WriteOnly or IO_ReadWrite) and write something into the buffer, buf is also modified because QByteArray is an explicitly shared class.

See also

buffer(), open(), close()

size()

uint QBuffer::size ( ) const

inlinevirtual

Implements QIODevice.

ungetch()

int QBuffer::ungetch ( int  ch )

virtual

Implements QIODevice.

writeBlock()

int QBuffer::writeBlock ( const char *  p, uint  len  )

virtual

Writes len bytes from p into the buffer at the current index, overwriting any characters there and extending the buffer if necessary. Returns the number of bytes actually written.

Returns -1 if a serious error occurred.

See also

readBlock()

Implements QIODevice.

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

• qtools/qbuffer.h
• qtools/qbuffer.cpp