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</tr></table><h1 class="title">A non-GUI example<br /><span class="subtitle"></span>
</h1>
<p>This example shows how to use the single-application functionality in a console application. It does not require the <tt>QtGui</tt> library at all.</p>
<p>The only differences from the GUI application usage demonstrated in the other examples are:</p>
<p>1) The <tt>.pro</tt> file should include <tt>qtsinglecoreapplication.pri</tt> instead of <tt>qtsingleapplication.pri</tt></p>
<p>2) The class name is <tt>QtSingleCoreApplication</tt> instead of <tt>QtSingleApplication</tt>.</p>
<p>3) No calls are made regarding window activation, for obvious reasons.</p>
<p>console.pro:</p>
<pre> TEMPLATE = app
CONFIG += console
SOURCES += main.cpp
include(../../src/qtsinglecoreapplication.pri)
QT -= gui</pre>
<p>main.cpp:</p>
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#include &quot;qtsinglecoreapplication.h&quot;
#include &lt;QtCore/QDebug&gt;
void report(const QString&amp; msg)
{
qDebug(&quot;[%i] %s&quot;, (int)QCoreApplication::applicationPid(), qPrintable(msg));
}
class MainClass : public QObject
{
Q_OBJECT
public:
MainClass()
: QObject()
{}
public slots:
void handleMessage(const QString&amp; message)
{
report( &quot;Message received: \&quot;&quot; + message + &quot;\&quot;&quot;);
}
};
int main(int argc, char **argv)
{
report(&quot;Starting up&quot;);
QtSingleCoreApplication app(argc, argv);
if (app.isRunning()) {
QString msg(QString(&quot;Hi master, I am %1.&quot;).arg(QCoreApplication::applicationPid()));
bool sentok = app.sendMessage(msg, 2000);
QString rep(&quot;Another instance is running, so I will exit.&quot;);
rep += sentok ? &quot; Message sent ok.&quot; : &quot; Message sending failed; the other instance may be frozen.&quot;;
report(rep);
return 0;
} else {
report(&quot;No other instance is running; so I will.&quot;);
MainClass mainObj;
QObject::connect(&amp;app, SIGNAL(messageReceived(const QString&amp;)),
&amp;mainObj, SLOT(handleMessage(const QString&amp;)));
return app.exec();
}
}
#include &quot;main.moc&quot;</pre>
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