[c++] QString to char* conversion

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?

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".

If your string contains non-ASCII characters - it's better to do it this way: s.toUtf8().data() (or s->toUtf8().data())

EDITED

this way also works

QString str ("Something");

char* ch = str.toStdString().C_str();

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<<"<---";

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.

It is a viable way to use std::vector as an intermediate container:

QString dataSrc("FooBar");
QString databa = dataSrc.toUtf8();
std::vector<char> data(databa.begin(), databa.end());
char* pDataChar = data.data();

The easiest way to convert a QString to char* is qPrintable(const QString& str), which is a macro expanding to str.toLocal8Bit().constData().

Qt provides the simplest API

const char *qPrintable(const QString &str)
const char *qUtf8Printable(const QString &str)

If you want non-const data pointer use

str.toLocal8Bit().data()
str.toUtf8().data()

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);