C++ – Qt – qWarning with QString – Convert QString to Char*

When I looked to My Google Analytics, I saw that some developers search “qwarning qstring” etc.

Here are some examples.

#include <QtCore/QCoreApplication>

#include <QTime>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);

	const char* IamChar = "I am a char";
	QString IamString("I am a QString");

	qWarning(IamChar);

	qWarning(IamString.toLatin1());

	qWarning("Direct char warning");

	qWarning(QString("Direct QString").toLatin1());

	qWarning(QString("Special %1 = %2").arg("value").arg(5).toLatin1());

	qWarning(QTime::currentTime().toString().toLatin1());

	// With preprocessor
	qWarning(QString("From %1 at line %2 (%3 -- %4)").arg(__FILE__).arg(__LINE__).arg(__DATE__).arg(__TIME__).toLatin1());

    return a.exec();
}

Output :
I am a char
I am a QString
Direct char warning
Direct QString
Special value = 5
10:53:23
From .\main.cpp at line 26 (Jul 21 2010 — 10:53:22)