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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<h1 align=center>QBuffer Class Reference</h1><br clear="all">
<p>
The QBuffer class is an I/O device that operates on a <a href="qbytearray.html">QByteArray</a>
<a href="#details">More...</a>
<p>
<code>#include <<a href="qbuffer-h.html">qbuffer.h</a>></code>
<p>
Inherits <a href="qiodevice.html">QIODevice</a>.
<p><a href="qbuffer-members.html">List of all member functions.</a>
<h2>Public Members</h2>
<ul>
<li><div class="fn"><a href="#1da55f"><b>QBuffer</b></a>()</div>
<li><div class="fn"><a href="#c15c53"><b>QBuffer</b></a>(QByteArray)</div>
<li><div class="fn"><a href="#cc4b03"><b>~QBuffer</b></a>()</div>
<li><div class="fn">QByteArray<a href="#2ca40b"><b>buffer</b></a>()const</div>
<li><div class="fn">bool<a href="#00fe91"><b>setBuffer</b></a>(QByteArray)</div>
</ul>
<hr><h2><a name="details"></a>Detailed Description</h2>
The QBuffer class is an I/O device that operates on a <a href="qbytearray.html">QByteArray</a>
<p>
QBuffer allows reading and writing a memory buffer. It is normally
used together with a <a href="qtextstream.html">QTextStream</a> or a <a href="qdatastream.html">QDataStream</a>. QBuffer has an
associated QByteArray which holds the buffer data. The <a href="#ec2eec">size</a>() of the
buffer is automatically adjusted as data is written.
<p>The constructor <code>QBuffer(QByteArray)</code> creates a QBuffer with an
existing byte array. The byte array can also be set with <a href="#00fe91">setBuffer</a>().
Writing to the QBuffer will modify the original byte array, since
QByteArray is <a href="shclass.html">explicitly shared.</a>
<p>Use <a href="#61e313">open</a>() to open the buffer before use, and to set the mode
(read-only,write-only, etc.). <a href="#1384d7">close</a>() closes the buffer. The buffer
must be closed before reopening or calling setBuffer().
<p>The 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 parameter. For
convenience, there are also QDataStream and QTextStream constructors
that take a QByteArray parameter. These constructors create and open
an internal QBuffer.
<p>Note that QTextStream can also operate on a <a href="qstring.html">QString</a> (a Unicode
string); a QBuffer cannot.
<p>You can also use QBuffer directly through the standard <a href="qiodevice.html">QIODevice</a>
functions <a href="#e728f4">readBlock</a>(), <a href="#b7c1fa">writeBlock</a>() <a href="#76f564">readLine</a>(), <a href="#814bfa">at</a>(), <a href="#e7090a">getch</a>(), <a href="#43fe39">putch</a>() and
<a href="#432a5a">ungetch</a>().
<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> and <a href="shclass.html">Shared Classes</a>
<p>Examples:
<a href="grapher-grapher-cpp.html#QBuffer">grapher/grapher.cpp</a>
<hr><h2>Member Function Documentation</h2>
<h3 class="fn"><a name="1da55f"></a>QBuffer::QBuffer()</h3>
<p>Constructs an empty buffer.
<h3 class="fn"><a name="c15c53"></a>QBuffer::QBuffer(<a href="qbytearray.html">QByteArray</a>buf)</h3>
<p>Constructs a buffer that operates on <em>buf.</em>
If you open the buffer in write mode (<code>IO_WriteOnly</code> or
<code>IO_ReadWrite)</code> and write something into the buffer, <em>buf</em>
will be modified.
<p>Example:
<pre> <a href="qcstring.html">QCString</a> str = "abc";
<a href="qbuffer.html">QBuffer</a> b( str );
b.<a href="#61e313">open</a>( IO_WriteOnly );
b.<a href="#814bfa">at</a>( 3 ); // position at \0
b.<a href="#b7c1fa">writeBlock</a>( "def", 4 ); // write including \0
b.<a href="#1384d7">close</a>();
// Now, str == "abcdef"
</pre>
<p>See also <a href="#00fe91">setBuffer</a>().
<h3 class="fn"><a name="cc4b03"></a>QBuffer::~QBuffer()</h3>
<p>Destructs the buffer.
<h3 class="fn">bool<a name="814bfa"></a>QBuffer::at(intpos) <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
<p>Reimplemented from <a href="qiodevice.html#2cc92b">QIODevice.</a>
<h3 class="fn">int<a name="b08b4c"></a>QBuffer::at()const <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
<p>Reimplemented from <a href="qiodevice.html#0a097f">QIODevice.</a>
<h3 class="fn"><a href="qbytearray.html">QByteArray</a><a name="2ca40b"></a>QBuffer::buffer()const</h3>
<p>Returns this buffer's byte array.
<p>See also <a href="#00fe91">setBuffer</a>().
<h3 class="fn">void<a name="1384d7"></a>QBuffer::close() <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
Closes an open buffer.
<p>See also <a href="#61e313">open</a>().
<p>Examples:
<a href="grapher-grapher-cpp.html#close">grapher/grapher.cpp</a>
<p>Reimplemented from <a href="qiodevice.html#2e20a6">QIODevice.</a>
<h3 class="fn">void<a name="f0c19e"></a>QBuffer::flush() <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
The flush function does nothing for a QBuffer.
<p>Reimplemented from <a href="qiodevice.html#e99637">QIODevice.</a>
<h3 class="fn">int<a name="e7090a"></a>QBuffer::getch() <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
<p>Reimplemented from <a href="qiodevice.html#c20352">QIODevice.</a>
<h3 class="fn">bool<a name="61e313"></a>QBuffer::open(intm) <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
Opens the buffer in the mode <em>m.</em> Returns TRUE if successful,
otherwise FALSE. The buffer must be opened before use.
<p>The mode parameter <em>m</em> must be a combination of the following flags.
<ul>
<li><code>IO_ReadOnly</code> opens a buffer in read-only mode.
<li><code>IO_WriteOnly</code> opens a buffer in write-only mode.
<li><code>IO_ReadWrite</code> opens a buffer in read/write mode.
<li><code>IO_Append</code> sets the buffer index to the end of the buffer.
<li><code>IO_Truncate</code> truncates the buffer.
</ul>
<p>See also <a href="#1384d7">close</a>() and <a href="qiodevice.html#6e261a">isOpen</a>().
<p>Examples:
<a href="grapher-grapher-cpp.html#open">grapher/grapher.cpp</a>
<p>Reimplemented from <a href="qiodevice.html#815d1e">QIODevice.</a>
<h3 class="fn">int<a name="43fe39"></a>QBuffer::putch(intch) <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
Writes the character <em>ch</em> into the buffer, overwriting
the character at the current index, extending the buffer
if necessary.
<p>Returns <em>ch,</em> or -1 if some error occurred.
<p>See also <a href="#e7090a">getch</a>() and <a href="#432a5a">ungetch</a>().
<p>Examples:
<a href="grapher-grapher-cpp.html#putch">grapher/grapher.cpp</a>
<p>Reimplemented from <a href="qiodevice.html#49e172">QIODevice.</a>
<h3 class="fn">int<a name="e728f4"></a>QBuffer::readBlock(char*p, uintlen) <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
<p>Reimplemented from <a href="qiodevice.html#01ed23">QIODevice.</a>
<h3 class="fn">int<a name="76f564"></a>QBuffer::readLine(char*p, uintmaxlen) <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
<p>Reimplemented from <a href="qiodevice.html#a84cbb">QIODevice.</a>
<h3 class="fn">bool<a name="00fe91"></a>QBuffer::setBuffer(<a href="qbytearray.html">QByteArray</a>buf)</h3>
<p>Replaces the buffer's contents with <em>buf.</em>
<p>This may not be done when <a href="qiodevice.html#6e261a">isOpen</a>() is TRUE.
<p>Note that if you open the buffer in write mode (<code>IO_WriteOnly</code> or
IO_ReadWrite) and write something into the buffer, <em>buf</em> is also
modified because <a href="qbytearray.html">QByteArray</a> is an explicitly shared class.
<p>See also <a href="#2ca40b">buffer</a>(), <a href="#61e313">open</a>() and <a href="#1384d7">close</a>().
<h3 class="fn">uint<a name="ec2eec"></a>QBuffer::size()const <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
<p>Reimplemented from <a href="qiodevice.html#e7aea5">QIODevice.</a>
<h3 class="fn">int<a name="432a5a"></a>QBuffer::ungetch(intch) <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
<p>Reimplemented from <a href="qiodevice.html#09ed27">QIODevice.</a>
<h3 class="fn">int<a name="b7c1fa"></a>QBuffer::writeBlock(constchar*p, uintlen) <code>[virtual]</code></h3>
<p>Reimplemented for internal reasons; the API is not affected.
<p>Writes <em>len</em> bytes from <em>p</em> into the buffer at the current index,
overwriting any characters there and extending the buffer if necessary.
Returns the number of bytes actually written.
<p>Returns -1 if a serious error occurred.
<p>See also <a href="#e728f4">readBlock</a>().
<p>Reimplemented from <a href="qiodevice.html#6cc265">QIODevice.</a>
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