QString to char* conversion
Question
I was trying to convert a QString to char* type by the following methods, but they don't seem to work.
//QLineEdit *line=new QLineEdit();{just to describe what is line here}
QString temp=line->text();
char *str=(char *)malloc(10);
QByteArray ba=temp.toLatin1();
strcpy(str,ba.data());
Can you elaborate the possible flaw with this method, or give an alternative method?
Solution
Well, the Qt FAQ says:
int main(int argc, char **argv)
{
QApplication app(argc, argv);
QString str1 = "Test";
QByteArray ba = str1.toLocal8Bit();
const char *c_str2 = ba.data();
printf("str2: %s", c_str2);
return app.exec();
}
So perhaps you're having other problems. How exactly doesn't this work?
OTHER TIPS
Maybe
my_qstring.toStdString().c_str();
or safer, as Federico points out:
std::string str = my_qstring.toStdString();
const char* p = str.c_str();
It's far from optimal, but will do the work.
The easiest way to convert a QString to char* is qPrintable(const QString& str),
which is a macro expanding to str.toLocal8Bit().constData()
.
David's answer works fine if you're only using it for outputting to a file or displaying on the screen, but if a function or library requires a char* for parsing, then this method works best:
// copy QString to char*
QString filename = "C:\dev\file.xml";
char* cstr;
string fname = filename.toStdString();
cstr = new char [fname.size()+1];
strcpy( cstr, fname.c_str() );
// function that requires a char* parameter
parseXML(cstr);
EDITED
this way also works
QString str ("Something");
char* ch = str.toStdString().C_str();
Your string may contain non Latin1 characters, which leads to undefined data. It depends of what you mean by "it deosn't seem to work".
the Correct Solution Would be like this
QString k;
k = "CRAZYYYQT";
char ab[16];
sprintf(ab,"%s",(const char *)((QByteArray)(k.toLatin1()).data()) );
sprintf(ab,"%s",(const char *)((QByteArray)(k.toStdString()).data()));
sprintf(ab,"%s",(const char *)k.toStdString().c_str() );
qDebug()<<"--->"<<ab<<"<---";
If your string contains non-ASCII characters - it's better to do it this way:
s.toUtf8().data()
(or s->toUtf8().data()
)