Use QString::data() Pointer as Pointer to wchar_t/WCHAR

[franku]

Hi There, can comeone give me a hint on how to use the QString::data() ?

As I know from the Documentation Qt stores strings internally as Unicode. So my question is: Can I use the Pointer returned by data() as a pointer to WCHAR (wchar_t) ?

static void toWideChar(const QString& qsIn, LPWSTR* wideCharOut)
{
    Q_ASSERT(!qsIn.isEmpty());
    *wideCharOut = (LPWSTR)qsIn.data();
}

static void toWideChar(const QString& qsIn, LPWSTR* wideCharOut)
{
    Q_ASSERT(!qsIn.isEmpty());
    *wideCharOut = (LPWSTR)qsIn.data();
}

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I found in qstring.h the ushort data pointer:

struct Data {
        QBasicAtomicInt ref;
        int alloc, size;
        ushort *data; 
        ushort clean : 1;
        ushort simpletext : 1;
        ushort righttoleft : 1;
        ushort asciiCache : 1;
        ushort capacity : 1;
        ushort reserved : 11;
        ushort array[1];
    };

struct Data {
        QBasicAtomicInt ref;
        int alloc, size;
        ushort *data; 
        ushort clean : 1;
        ushort simpletext : 1;
        ushort righttoleft : 1;
        ushort asciiCache : 1;
        ushort capacity : 1;
        ushort reserved : 11;
        ushort array[1];
    };

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This Pointer will be returned as a reinterpretet QChar Pointer:

inline const QChar *QString::data() const
{ return reinterpret_cast<const QChar*>(d->data); }

inline const QChar *QString::data() const
{ return reinterpret_cast<const QChar*>(d->data); }

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All other attempts (i.e. toWCharArray()) seem to copy all the content and this is what I try to avoid.

Any Commtents (however, even good practive-hints) ? Thanks.

[Zlatomir]

They both (WCHAR and QChar) are unsigned short integers (2 bytes), so this should work:

QString str("Test String");
	WCHAR* wcar = (WCHAR*)(str.constData());
	std::wcout << wcar << '\n';

QString str("Test String");
	WCHAR* wcar = (WCHAR*)(str.constData());
	std::wcout << wcar << '\n';

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For read-only access, constData() is faster because it never causes a deep copy to occur.

Quoted from here, so use constData member function.

Note that this pointer is valid only until you modify the original QString.