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.

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Answer 1

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()

Answer 2

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".

Answer 3

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();

Answer 4

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);

Answer 5

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

Answer 6

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