CODEWITHSUNDEEP
c++qtcharqstring
Amre
Amre

Reputation: 1680

How do i convert a QString to a char*

I have a QString that I would like to convert into a char* not a QChar* because I'll be passing it into a method that takes a char*, however I can't convert it without it getting a const char*. For example I have tried:

QString name = "name";
QByteArray byteArray = name.toUtf8();
myMailboxName = byteArray.constData();

and

QString name = "name";
QByteArray byteArray = name.toUtf8();
myMailboxName = byteArray.data();

where myMailboxName is a private char* in my class. However I get an error because it is returning a const char* and can't assign it to a char*. How can I fix this?

Upvotes: 1

Views: 5292

Answers (6)

shivaranjani
shivaranjani

Reputation: 75

try this code snippet

const char *myMailboxName = name.toLatin1().data();

Upvotes: 2

Ani
Ani

Reputation: 2988

consider following example
QString str = "BlahBlah;"

try this
char* mychar = strdup(qPrintable(str));

or this
char* mychr = str.toStdString().c_str();

or this
char* mychar = strdup(str.ascii());

Every syntax worked for me ;)

Upvotes: 0

Zeks
Zeks

Reputation: 2385

I use something like this wrapper:

template<typename T, typename Y>
void CharPasser(std::function<T(char *)> funcToExecute,  const Y& str)
{
    char* c = 0;
    c = qstrdup(c, str.c_str());
    funcToExecute(c);
    delete[] c;
}

int SomeFunc(char* ){}

then use it like:

CharPasser<int, std::string>(SomeFunc, QString("test").tostdString())

At least this saves a bit of typing... :)

Upvotes: 0

NG_
NG_

Reputation: 7181

You can really use strdup (stackoverflow question about it), as Mike recommends, but also you can do that:

// 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() );

Got there: stackoverflow similar question.

Upvotes: 1

Mike
Mike

Reputation: 702

Use strdup. It does the allocation and the copy at the same time. Just remember to free it once you're done.

Upvotes: 1

dzada
dzada

Reputation: 5874

This is because data() returns the address of the buffer in the bytearray, you can read it, but obviously you should not write it. You have your own buffer outside the bytearray. If you want the data, you should copy the buffer of bytearray into the myMailBoName.

use memcpy function

Upvotes: 3

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