Converting QString to PCWSTR on Windows

Question

Why does the following code from this answer work:

QString username = "Bond";
std::wstring username = username.toStdWString();
PCWSTR username = username.c_str();

When the following does not:

QString username = "Bond";
PCWSTR username = username.toStdWString().c_str();

Nitpicking: You code will not compile in any case - you have duplicate names of variables. — HiFile.app - best file manager, Aug 09 '21 at 12:24

score 0 · Accepted Answer · answered Aug 09 '21 at 06:53

0

The temporary object gets destroyed, the result of the c_str() is invalid after that point.

answered Aug 09 '21 at 06:53

rpress

1

Legend! Even after years using C++ things like this continue to surprise – Jez Aug 09 '21 at 07:16

HiFile.app - best file manager · Answer 2 · 2021-08-09T12:40:53.943

0

The answer by rpress is of course correct. I am however using this conversion:

const QString usernameStr = "Bond";
auto usernameStrPtr = reinterpret_cast<PCWSTR>(usernameStr.utf16());

In most cases this will avoid one unnecessary allocation and conversion to std:wstring. I assume your expected coding is UTF16 anyway...

edited Aug 09 '21 at 12:40

answered Aug 09 '21 at 12:28

That one unecessary allocation is precisely what I was trying to avoid when I stumbled upon this problem, so this is a helpful way of doing it – Jez Aug 10 '21 at 14:31

2 Answers2