qdatastream.3qt

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.TH QDataStream 3qt "6 July 1999" "Troll Tech AS" \" -*- nroff -*-
.\" Copyright 1992-1999 Troll Tech AS.  All rights reserved.  See the
.\" license file included in the distribution for a complete license
.\" statement.
.\"
.ad l
.nh
.SH NAME
QDataStream \- Basic functions for serialization of binary data to a QIODevice
.SH SYNOPSIS
.br
.PP
\fC#include <qdatastream.h>\fR
.PP
.SS "Public Members"
.in +1c
.ti -1c
.BI "\fBQDataStream\fR ()"
.br
.ti -1c
.BI "\fBQDataStream\fR ( QIODevice * )"
.br
.ti -1c
.BI "\fBQDataStream\fR ( QByteArray, int mode )"
.br
.ti -1c
.BI "virtual \fB~QDataStream\fR ()"
.br
.ti -1c
.BI "QIODevice* \fBdevice\fR () const"
.br
.ti -1c
.BI "void \fBsetDevice\fR ( QIODevice * )"
.br
.ti -1c
.BI "void \fBunsetDevice\fR ()"
.br
.ti -1c
.BI "bool \fBatEnd\fR () const"
.br
.ti -1c
.BI "bool \fBeof\fR () const"
.br
.ti -1c
.BI "enum \fBByteOrder\fR { BigEndian, LittleEndian }"
.br
.ti -1c
.BI "int \fBbyteOrder\fR () const"
.br
.ti -1c
.BI "void \fBsetByteOrder\fR ( int )"
.br
.ti -1c
.BI "bool \fBisPrintableData\fR () const"
.br
.ti -1c
.BI "void \fBsetPrintableData\fR ( bool )"
.br
.ti -1c
.BI "int \fBversion\fR () const"
.br
.ti -1c
.BI "void \fBsetVersion\fR ( int )"
.br
.ti -1c
.BI "QDataStream& \fBoperator>>\fR ( Q_INT8 & i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator>>\fR ( Q_UINT8 & i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator>>\fR ( Q_INT16 & i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator>>\fR ( Q_UINT16 & i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator>>\fR ( Q_INT32 & i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator>>\fR ( Q_UINT32 & i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator>>\fR ( float & f )"
.br
.ti -1c
.BI "QDataStream& \fBoperator>>\fR ( double & f )"
.br
.ti -1c
.BI "QDataStream& \fBoperator>>\fR ( char *& str )"
.br
.ti -1c
.BI "QDataStream& \fBoperator<<\fR ( Q_INT8 i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator<<\fR ( Q_UINT8 i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator<<\fR ( Q_INT16 i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator<<\fR ( Q_UINT16 i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator<<\fR ( Q_INT32 i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator<<\fR ( Q_UINT32 i )"
.br
.ti -1c
.BI "QDataStream& \fBoperator<<\fR ( float f )"
.br
.ti -1c
.BI "QDataStream& \fBoperator<<\fR ( double f )"
.br
.ti -1c
.BI "QDataStream& \fBoperator<<\fR ( const char * str )"
.br
.ti -1c
.BI "QDataStream& \fBreadBytes\fR ( char *&, uint & len )"
.br
.ti -1c
.BI "QDataStream& \fBreadRawBytes\fR ( char *, uint len )"
.br
.ti -1c
.BI "QDataStream& \fBwriteBytes\fR ( const char *, uint len )"
.br
.ti -1c
.BI "QDataStream& \fBwriteRawBytes\fR ( const char *, uint len )"
.br
.in -1c
.SH DESCRIPTION
The QDataStream class provides basic functions for serialization of binary data to a QIODevice.
.PP
A data stream is a binary stream of encoded information which is 100% independent of the host computer operation system, CPU or byte order. A stream that is written by a PC under DOS/Windows can easily be read by a Sun SPARC running Solaris.
.PP
The QDataStream class implements serialization of primitive types, like \fCchar, short, int, char*\fR etc. Serialization of more complex data is accomplished by breaking up the data into primitive units.
.PP
The programmer can select which byte order to use when serializing data. The default setting is big endian (MSB first). Changing it to little endian breaks the portability. We therefore recommend keeping this setting unless you have special needs or requirements.
.PP
A data stream cooperates closely with a QIODevice. A QIODevice represents an input/output medium one can read data from and write data to. The QFile class is an example of an IO device.
.PP
Example (write data to a stream):
.PP
.nf
.br
    QFile f( "file.dta" );
.br
    f.open( IO_WriteOnly );                     // open file for writing
.br
    QDataStream s( &f );                        // serialize using f
.br
    s << "the answer is";                       // serialize string
.br
    s << (Q_INT32)42;                           // serialize integer
.br
    f.close();                                  // done
.fi
.PP
Example (read data from a stream):
.PP
.nf
.br
    QFile f( "file.dta" );
.br
    f.open( IO_ReadOnly );                      // open file for reading
.br
    QDataStream s( &f );                        // serialize using f
.br
    char   *str;
.br
    Q_INT32 a;
.br
    s >> str >> a;                              // "the answer is" and 42
.br
    f.close();                                  // done
.br
    delete str;                                 // delete string
.fi
.PP
In the last example, if you read into a QString instead of a \fCchar*\fR you do not have to delete it.
.PP
See also: QTextStream.
.SH MEMBER FUNCTION DOCUMENTATION
.SH "QDataStream::QDataStream ()"
Constructs a data stream that has no IO device.
.SH "QDataStream::QDataStream ( QIODevice * d )"
Constructs a data stream that uses the IO device \fId.\fR
.SH "QDataStream::QDataStream ( QByteArray a, int mode )"
Constructs a data stream that operates on a byte array through an internal QBuffer device.
.PP
Example:
.PP
.nf
.br
    static char bindata[] = { 231, 1, 44, ... };
.br
    QByteArray  a;
.br
    a.setRawData( bindata, sizeof(bindata) );   // a points to bindata
.br
    QDataStream s( a, IO_ReadOnly );            // open on a's data
.br
    s >> <something>;                           // read raw bindata
.br
    a.resetRawData( bindata, sizeof(bindata) ); // finished
.fi
.PP
The QArray::setRawData() function is not for the inexperienced.
.SH "QDataStream::~QDataStream () \fC[virtual]\fR"
Destroys the data stream.
.PP
The destructor will not affect the current IO device, unless it is an internal IO device processing a QByteArray passed in the constructor.
.SH "bool QDataStream::atEnd () const"
Returns TRUE if the IO device has reached the end position (end of stream or file) or if there is no IO device set.
.PP
Returns FALSE if the current position of the read/write head of the IO device is somewhere before the end position.
.PP
See also: QIODevice::atEnd().
.SH "int QDataStream::byteOrder () const"
Returns the current byte order setting.
.PP
See also: setByteOrder().
.SH "QIODevice * QDataStream::device () const"
Returns the IO device currently set.
.PP
See also: setDevice() and unsetDevice().
.SH "bool QDataStream::eof () const"
\fBThis function is obsolete.\fR It is provided to keep old programs working. We strongly advise against using it in new code.
.PP
Returns TRUE if the IO device has reached the end position (end of stream or file) or if there is no IO device set.
.PP
Returns FALSE if the current position of the read/write head of the IO device is somewhere before the end position.
.PP
See also: QIODevice::atEnd().
.SH "bool QDataStream::isPrintableData () const"
Returns TRUE if the printable data flag has been set.
.PP
See also: setPrintableData().
.SH "QDataStream & QDataStream::operator<< ( Q_INT16 i )"
Writes a signed 16-bit integer to the stream and returns a reference to the stream.
.SH "QDataStream & QDataStream::operator<< ( Q_INT32 i )"
Writes a signed 32-bit integer to the stream and returns a reference to the stream.
.SH "QDataStream & QDataStream::operator<< ( Q_INT8 i )"
Writes a signed byte to the stream.
.SH "QDataStream & QDataStream::operator<< ( Q_UINT16 i )"
Writes an unsigned 16-bit integer to the stream and returns a reference to the stream.
.SH "QDataStream & QDataStream::operator<< ( Q_UINT32 i )"
Writes an unsigned 32-bit integer to the stream and returns a reference to the stream.
.SH "QDataStream & QDataStream::operator<< ( Q_UINT8 i )"
Writes an unsigned byte to the stream and returns a reference to the stream.
.SH "QDataStream & QDataStream::operator<< ( const char * s )"
Writes the '\\0'-terminated string \fIs\fR to the stream and returns a reference to the stream.
.PP
The string is serialized using writeBytes().
.SH "QDataStream & QDataStream::operator<< ( double f )"
Writes a 64-bit floating point number to the stream using the standard IEEE754 format. Returns a reference to the stream.
.SH "QDataStream & QDataStream::operator<< ( float f )"
Writes a 32-bit floating point number to the stream using the standard IEEE754 format. Returns a reference to the stream.
.SH "QDataStream & QDataStream::operator>> ( Q_INT16 & i )"
Reads a signed 16-bit integer from the stream and returns a reference to the stream.
.SH "QDataStream & QDataStream::operator>> ( Q_INT32 & i )"
Reads a signed 32-bit integer from the stream and returns a reference to the stream.
.SH "QDataStream & QDataStream::operator>> ( Q_INT8 & i )"
Reads a signed byte from the stream.
.SH "QDataStream & QDataStream::operator>> ( Q_UINT16 & i )"
Reads an unsigned 16-bit integer from the stream and returns a reference to the stream.
.SH "QDataStream & QDataStream::operator>> ( Q_UINT32 & i )"
Reads an unsigned 32-bit integer from the stream and returns a reference to the stream.
.SH "QDataStream & QDataStream::operator>> ( Q_UINT8 & i )"
Reads an unsigned byte from the stream and returns a reference to the stream.
.SH "QDataStream & QDataStream::operator>> ( char *& s )"
Reads the '\\0'-terminated string \fIs\fR from the stream and returns a reference to the stream.
.PP
The string is read using readBytes(), which allocates space using \fCnew.\fR
.SH "QDataStream & QDataStream::operator>> ( double & f )"
Reads a 64-bit floating point number from the stream using the standard IEEE754 format. Returns a reference to the stream.
.SH "QDataStream & QDataStream::operator>> ( float & f )"
Reads a 32-bit floating point number from the stream using the standard IEEE754 format. Returns a reference to the stream.
.SH "QDataStream & QDataStream::readBytes ( char *& s, uint & l )"
Reads the buffer \fIs\fR from the stream and returns a reference to the stream.
.PP
The buffer \fIs\fR is allocated using \fCnew.\fR Destroy it with the \fCdelete\fR operator. If the length is zero or \fIs\fR cannot be allocated, \fIs\fR is set to 0.
.PP
The \fIl\fR parameter will be set to the length of the buffer.
.PP
The serialization format is an Q_UINT32 length specifier first, then the data (\fIlength\fR bytes).
.PP
See also: readRawBytes() and writeBytes().
.SH "QDataStream & QDataStream::readRawBytes ( char * s, uint len )"
Reads \fIlen\fR bytes from the stream into \fIe\fR s and returns a reference to the stream.
.PP
The buffer \fIs\fR must be preallocated.
.PP
See also: readBytes(), QIODevice::readBlock() and writeRawBytes().
.SH "void QDataStream::setByteOrder ( int bo )"
Sets the serialization byte order to \fIbo.\fR
.PP
The \fIbo\fR parameter can be \fCQDataStream::BigEndian\fR or \fCQDataStream::LittleEndian.\fR
.PP
The default setting is big endian. We recommend leaving this setting unless you have special requirements.
.PP
See also: byteOrder().
.SH "void QDataStream::setDevice ( QIODevice * d )"
void QDataStream::setDevice(QIODevice *d ) Sets the IO device to \fId.\fR
.PP
See also: device() and unsetDevice().
.SH "void QDataStream::setPrintableData ( bool enable )"
Sets or clears the printable data flag.
.PP
If this flag is set, the write functions will generate output that consists of printable characters (7 bit ASCII).
.PP
We recommend enabling printable data only for debugging purposes (it is slower and creates bigger output).
.SH "void QDataStream::setVersion ( int v )"
Sets the version number of the data serialization format.
.PP
In Qt 2.0, the datastream serialization format of many Qt classes was changed. In order to read data that was created with the QDatastream of Qt 1.x, call this function with the version number \\v set to 1.
.PP
See also: version().
.SH "void QDataStream::unsetDevice ()"
Unsets the IO device. This is the same as calling setDevice( 0 ).
.PP
See also: device() and setDevice().
.SH "int QDataStream::version () const"
Returns the version number of the data serialization format. In Qt 2.0, this number is 2.
.PP
See also: setVersion().
.SH "QDataStream & QDataStream::writeBytes ( const char * s, uint len )"
Writes the length specifier \fIlen\fR and the buffer \fIs\fR to the stream and returns a reference to the stream.
.PP
The \fIlen\fR is serialized as an Q_UINT32, followed by \fIlen\fR bytes from \fIs.\fR
.PP
See also: writeRawBytes() and readBytes().
.SH "QDataStream & QDataStream::writeRawBytes ( const char * s, uint len )"
Writes \fIlen\fR bytes from \fIs\fR to the stream and returns a reference to the stream.
.PP
See also:  writeBytes(), QIODevice::writeBlock() and readRawBytes().
.SH "SEE ALSO"
.BR http://www.troll.no/qt/qdatastream.html
.SH COPYRIGHT
Copyright 1992-1999 Troll Tech AS.  See the license file included in
the distribution for a complete license statement.
.SH AUTHOR
Generated automatically from the source code.