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| 2 | <!-- /home/espenr/tmp/qt-3.3.8-espenr-2499/qt-x11-free-3.3.8/src/tools/qbuffer.cpp:41 -->
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| 6 | <title>QBuffer Class</title>
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| 16 | <table border="0" cellpadding="0" cellspacing="0" width="100%">
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| 17 | <tr bgcolor="#E5E5E5">
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| 18 | <td valign=center>
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| 19 | <a href="index.html">
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| 20 | <font color="#004faf">Home</font></a>
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| 21 | | <a href="classes.html">
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| 22 | <font color="#004faf">All Classes</font></a>
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| 23 | | <a href="mainclasses.html">
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| 24 | <font color="#004faf">Main Classes</font></a>
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| 26 | <font color="#004faf">Annotated</font></a>
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| 31 | </td>
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| 32 | <td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QBuffer Class Reference</h1>
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| 33 |
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| 34 | <p>The QBuffer class is an I/O device that operates on a QByteArray.
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| 35 | <a href="#details">More...</a>
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| 36 | <p>All the functions in this class are <a href="threads.html#reentrant">reentrant</a> when Qt is built with thread support.</p>
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| 37 | <p><tt>#include <<a href="qbuffer-h.html">qbuffer.h</a>></tt>
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| 38 | <p>Inherits <a href="qiodevice.html">QIODevice</a>.
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| 39 | <p><a href="qbuffer-members.html">List of all member functions.</a>
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| 40 | <h2>Public Members</h2>
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| 41 | <ul>
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| 42 | <li class=fn><a href="#QBuffer"><b>QBuffer</b></a> ()</li>
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| 43 | <li class=fn><a href="#QBuffer-2"><b>QBuffer</b></a> ( QByteArray buf )</li>
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| 44 | <li class=fn><a href="#~QBuffer"><b>~QBuffer</b></a> ()</li>
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| 45 | <li class=fn>QByteArray <a href="#buffer"><b>buffer</b></a> () const</li>
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| 46 | <li class=fn>bool <a href="#setBuffer"><b>setBuffer</b></a> ( QByteArray buf )</li>
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| 47 | <li class=fn>virtual Q_LONG <a href="#writeBlock"><b>writeBlock</b></a> ( const char * p, Q_ULONG len )</li>
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| 48 | <li class=fn>Q_LONG <a href="#writeBlock-2"><b>writeBlock</b></a> ( const QByteArray & data )</li>
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| 49 | </ul>
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| 50 | <hr><a name="details"></a><h2>Detailed Description</h2>
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| 51 |
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| 52 |
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| 53 |
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| 54 | The QBuffer class is an I/O device that operates on a <a href="qbytearray.html">QByteArray</a>.
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| 55 | <p>
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| 56 |
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| 57 | <p> QBuffer is used to read and write to a memory buffer. It is
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| 58 | normally used with a <a href="qtextstream.html">QTextStream</a> or a <a href="qdatastream.html">QDataStream</a>. QBuffer has an
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| 59 | associated QByteArray which holds the buffer data. The <a href="qiodevice.html#size">size</a>() of
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| 60 | the buffer is automatically adjusted as data is written.
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| 61 | <p> The constructor <tt>QBuffer(QByteArray)</tt> creates a QBuffer using an
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| 62 | existing byte array. The byte array can also be set with
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| 63 | <a href="#setBuffer">setBuffer</a>(). Writing to the QBuffer will modify the original byte
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| 64 | array because QByteArray is <a href="shclass.html">explicitly
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| 65 | shared.</a>
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| 66 | <p> Use <a href="qiodevice.html#open">open</a>() to open the buffer before use and to set the mode
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| 67 | (read-only, write-only, etc.). <a href="qiodevice.html#close">close</a>() closes the buffer. The
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| 68 | buffer must be closed before reopening or calling setBuffer().
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| 69 | <p> A common way to use QBuffer is through <a href="qdatastream.html">QDataStream</a> or <a href="qtextstream.html">QTextStream</a>, which have constructors that take a QBuffer
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| 70 | parameter. For convenience, there are also QDataStream and
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| 71 | <a href="qtextstream.html">QTextStream</a> constructors that take a <a href="qbytearray.html">QByteArray</a> parameter. These
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| 72 | constructors create and open an internal QBuffer.
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| 73 | <p> Note that QTextStream can also operate on a <a href="qstring.html">QString</a> (a Unicode
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| 74 | string); a QBuffer cannot.
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| 75 | <p> You can also use QBuffer directly through the standard <a href="qiodevice.html">QIODevice</a>
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| 76 | functions <a href="qiodevice.html#readBlock">readBlock</a>(), <a href="#writeBlock">writeBlock</a>() <a href="qiodevice.html#readLine">readLine</a>(), <a href="qiodevice.html#at">at</a>(), <a href="qiodevice.html#getch">getch</a>(),
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| 77 | <a href="qiodevice.html#putch">putch</a>() and <a href="qiodevice.html#ungetch">ungetch</a>().
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| 78 | <p> <p>See also <a href="qfile.html">QFile</a>, <a href="qdatastream.html">QDataStream</a>, <a href="qtextstream.html">QTextStream</a>, <a href="qbytearray.html">QByteArray</a>, <a href="shclass.html">Shared Classes</a>, <a href="collection.html">Collection Classes</a>, and <a href="io.html">Input/Output and Networking</a>.
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| 79 |
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| 80 | <hr><h2>Member Function Documentation</h2>
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| 81 | <h3 class=fn><a name="QBuffer"></a>QBuffer::QBuffer ()
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| 82 | </h3>
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| 83 | Constructs an empty buffer.
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| 84 |
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| 85 | <h3 class=fn><a name="QBuffer-2"></a>QBuffer::QBuffer ( <a href="qbytearray.html">QByteArray</a> buf )
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| 86 | </h3>
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| 87 | Constructs a buffer that operates on <em>buf</em>.
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| 88 | <p> If you open the buffer in write mode (<a href="qfile.html#open"><a href="qfile.html#open">IO_WriteOnly</a></a> or
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| 89 | <a href="qfile.html#open">IO_ReadWrite</a>) and write something into the buffer, <em>buf</em>
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| 90 | will be modified.
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| 91 | <p> Example:
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| 92 | <pre>
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| 93 | <a href="qcstring.html">QCString</a> str = "abc";
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| 94 | QBuffer b( str );
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| 95 | b.<a href="qiodevice.html#open">open</a>( IO_WriteOnly );
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| 96 | b.<a href="qiodevice.html#at">at</a>( 3 ); // position at the 4th character (the terminating \0)
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| 97 | b.<a href="#writeBlock">writeBlock</a>( "def", 4 ); // write "def" including the terminating \0
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| 98 | b.<a href="qiodevice.html#close">close</a>();
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| 99 | // Now, str == "abcdef" with a terminating \0
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| 100 | </pre>
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| 101 |
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| 102 | <p> <p>See also <a href="#setBuffer">setBuffer</a>().
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| 103 |
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| 104 | <h3 class=fn><a name="~QBuffer"></a>QBuffer::~QBuffer ()
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| 105 | </h3>
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| 106 | Destroys the buffer.
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| 107 |
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| 108 | <h3 class=fn><a href="qbytearray.html">QByteArray</a> <a name="buffer"></a>QBuffer::buffer () const
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| 109 | </h3>
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| 110 |
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| 111 | <p> Returns this buffer's byte array.
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| 112 | <p> <p>See also <a href="#setBuffer">setBuffer</a>().
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| 113 |
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| 114 | <h3 class=fn>bool <a name="setBuffer"></a>QBuffer::setBuffer ( <a href="qbytearray.html">QByteArray</a> buf )
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| 115 | </h3>
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| 116 | Replaces the buffer's contents with <em>buf</em> and returns TRUE.
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| 117 | <p> Does nothing (and returns FALSE) if <a href="qiodevice.html#isOpen">isOpen</a>() is TRUE.
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| 118 | <p> Note that if you open the buffer in write mode (<a href="qfile.html#open"><a href="qfile.html#open">IO_WriteOnly</a></a> or
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| 119 | <a href="qfile.html#open">IO_ReadWrite</a>) and write something into the buffer, <em>buf</em> is also
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| 120 | modified because <a href="qbytearray.html">QByteArray</a> is an <a href="shclass.html#explicitly-shared">explicitly shared</a> class.
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| 121 | <p> <p>See also <a href="#buffer">buffer</a>(), <a href="qiodevice.html#open">open</a>(), and <a href="qiodevice.html#close">close</a>().
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| 122 |
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| 123 | <h3 class=fn>Q_LONG <a name="writeBlock"></a>QBuffer::writeBlock ( const char * p, Q_ULONG len )<tt> [virtual]</tt>
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| 124 | </h3>
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| 125 | Writes <em>len</em> bytes from <em>p</em> into the buffer at the current
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| 126 | index position, overwriting any characters there and extending the
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| 127 | buffer if necessary. Returns the number of bytes actually written.
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| 128 | <p> Returns -1 if an error occurred.
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| 129 | <p> <p>See also <a href="qiodevice.html#readBlock">readBlock</a>().
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| 130 |
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| 131 | <p>Reimplemented from <a href="qiodevice.html#writeBlock">QIODevice</a>.
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| 132 | <h3 class=fn>Q_LONG <a name="writeBlock-2"></a>QBuffer::writeBlock ( const <a href="qbytearray.html">QByteArray</a> & data )
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| 133 | </h3>
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| 134 | This is an overloaded member function, provided for convenience. It behaves essentially like the above function.
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| 135 | <p> This convenience function is the same as calling
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| 136 | <tt>writeBlock( data.data(), data.size() )</tt> with <em>data</em>.
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| 137 |
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| 138 | <!-- eof -->
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| 139 | <hr><p>
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| 140 | This file is part of the <a href="index.html">Qt toolkit</a>.
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| 141 | Copyright © 1995-2007
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| 142 | <a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center>
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| 143 | <table width=100% cellspacing=0 border=0><tr>
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| 144 | <td>Copyright © 2007
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| 145 | <a href="troll.html">Trolltech</a><td align=center><a href="trademarks.html">Trademarks</a>
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| 146 | <td align=right><div align=right>Qt 3.3.8</div>
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| 147 | </table></div></address></body>
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| 148 | </html>
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