how to convert QString to const char*　(utf8)

SGaist

Hi,

It should rather be:

QString myString("foo/bar");
QByteArray inUtf8 = myString.toUtf8();
const char *data = inUtf8.constData();

Because

const char *data = myString.toUtf8().constData();
on the next line the QByteArray returned by toUtf8 has been destroyed

mcosta

Yep, you're right.

Sorry

opengpu2

and i should use :
QString::fromUtf8((const char**)xxx);
to conver utf8 const char* to QString?

SGaist

What is xxx ?

opengpu2

This post is deleted!

opengpu2

@SGaist
eg. the const char* got from QString

QString myString("foo/bar");
QByteArray inUtf8 = myString.toUtf8();
const char *data = inUtf8.constData();

opengpu2

@SGaist const char*

SGaist

Why would you need to call fromUtf8 on the const char * you just got from that QString ?

opengpu2

@SGaist i need to convert with each other...thank you

opengpu2

@SGaist sometimes i need to convert the const char* (utf8) to QString

opengpu2

This post is deleted!

joaopagotto

//----------------------------
// QString to *char

QString aux;
aux.append("aa");
aux.append("bb");

char *texto;
texto = aux.toStdString().c_str();

//----------------------------
// *char to QString

char text[64];
strcpy(text, "text123");

QString aux;
aux.append(text);

SGaist

@joaopagotto where is the utf-8 handling ?

opengpu2

@SGaist QString::fromUtf8((const char*)xxx); is this correct ? thank you..

SGaist

Again, what is xxx ?

opengpu2

@SGaist it's const char* in utf8...eg. the const char* that converted from QString above...
thank you

opengpu2

It should rather be:

QString myString("foo/bar");
QByteArray inUtf8 = myString.toUtf8();
const char *data = inUtf8.constData();

Because

const char *data = myString.toUtf8().constData();
on the next line the QByteArray returned by toUtf8 has been destroyed

//////////////////////////////////////
if as a function param, is this right?
void function(myString.toUtf8().constData()) {}

SGaist

void function(myString.toUtf8().constData()) {} ?

It's not a valid function signature

opengpu2

@SGaist void func(const char* xxx);
func(myString.toUtf8().constData());

SGaist

It will work, but it's not the best thing to do from a readability point of view.