How to get Windows path using Qt/C++

Question

I am trying to get the windows path using Qt and C++. The below code compiles, but not gettting the windows folder path in Qt. The same code works in Visual Studio 2010

      wchar_t path[MAX_PATH];
      SHGetFolderPath(NULL, CSIDL_WINDOWS, NULL, 0, path);

The below code change seems working:

     int const bufferSize = 512;        
     QScopedPointer<WCHAR> dirPath(new WCHAR[bufferSize]);
     ZeroMemory( dirPath.operator ->(), bufferSize);
     SHGetFolderPath(NULL, CSIDL_WINDOWS, NULL, 0, dirPath.operator ->());

What do you mean by "in QT"? Qt is a library, it's not comparable to an IDE like Visual Studio. You can use Qt with a multitude of compilers, including Visual C++ compiler used by Visual Studio. — eq-, Jun 05 '12 at 17:06
I need to get the windows path using QT 4.6.3 using windows APIs — JChan, Jun 05 '12 at 17:07
Are you referring to the Qt Creator IDE? That is not the same as Qt. As it stands your question has nothing to do with Qt. And it's Qt, not QT. — Bart, Jun 05 '12 at 17:09
My devleopment environment is QT Creator/QT library, also I am using Windows APIs. — JChan, Jun 05 '12 at 17:10
[This answer](http://stackoverflow.com/a/2489700/177116) worked for me. — Andrew-Dufresne, Dec 23 '16 at 16:28

karlphillip · Answer 1 · 2012-06-05T18:14:39.110

2

There isn't a Qt function to do this, but what you are asking could be achieved by reading the environtment variable WINDIR:

QStringList env_list(QProcess::systemEnvironment());

int idx = env_list.indexOf(QRegExp("^WINDIR=.*", Qt::CaseInsensitive));
if (idx > -1)
{
    QStringList windir = env_list[idx].split('=');
    qDebug() << "Var : " << windir[0];
    qDebug() << "Path: " << windir[1];
}

Outputs:

Var :  "WINDIR"
Path:  "C:\WINDOWS"

edited Jun 05 '12 at 18:14

answered Jun 05 '12 at 17:14

karlphillip

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Not necessarily if Windows is installed somewhere else (is that possible?), or is called something else on a localized version. Lots of people hard coded "Program Files" in their apps and got bitten by 64bit – Martin Beckett Jun 05 '12 at 17:28
It's was people finding their app is now in "Program Files(x86)". Does "Windows" not get translated? – Martin Beckett Jun 05 '12 at 17:41
I rewrote the answer, it's worth checking it out. Maybe it's appropriate to delete your comments as well since they are outdated. – karlphillip Jun 05 '12 at 18:15

score 1 · Answer 2 · answered Jun 06 '12 at 08:04

QString windowsInstallPath;

#ifdef Q_WS_WIN
QDir d;
if (d.cd("%windir%"))
    windowsInstallPath = d.absolutePath();
#endif

if (!windowsInstallPath.isNull())
    qDebug() << windowsInstallPath;
else
    qDebug() << "Not compiled for Windows";

Should work.

score 1 · Answer 3 · answered Apr 19 '20 at 01:00

I think another very reasonable way to get the Windows directory would be to get it from the environment passed to the program:

QProcessEnvironment env = QProcessEnvironment::systemEnvironment();
qDebug() << env.value("windir");

https://doc.qt.io/qt-5/qprocessenvironment.html

score 0 · Answer 4 · answered Jun 05 '12 at 17:14

0

I don't think there is a specific Qt function to do this.

The nearest is QSysinfo which tells you the windows version. However SHGetFolderPath() shoudl work in Qt just as well as any other win API call.

ps In Windows vista-> this is replaced with SHGetKnownFolderPath

answered Jun 05 '12 at 17:14

Martin Beckett

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It seems an issue with the variable type wchar_t path[MAX_PATH], I think its compatible with QT – JChan Jun 05 '12 at 17:17
Possibly dependign on the UNICODE setting in vs2010 the function may not be included in wide char form – Martin Beckett Jun 05 '12 at 17:26

score 0 · Answer 5 · answered Sep 14 '17 at 09:17

0

Here is a one line solution:

QString winPath = QString::fromUtf8(qgetenv("windir"));

This can also be used for any environment variable. I am not sure if qgetenv is available in Qt4 but it is in Qt5.

answered Sep 14 '17 at 09:17

Uga Buga

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score 0 · Answer 6 · answered Jul 01 '21 at 12:43

If your application is not Terminal Services aware, you may get a different directory under TS environment. Found this out myself today, not that I've ever been bit by %windir% or %SystemRoot% or using the ShGetKnownFolderPath or GetWindowsDirectory APIs.

I've opted for using GetSystemWindowsDirectory which exists Windows 2000 and upward. Microsoft's page for the function is here.

Further explanation by Raymond Chen is here.

Finally, the code...

It's written in Delphi 6. Sorry about that :) It's what I'm coding in at the moment, but if you have code for GetWindowsDirectory in your language, then just a few copy + renames are needed as the function signatures are identical. Note: this code is ANSI (...single byte chars in Delphi 6).

function GetSystemWindowsDirectoryA(lpBuffer: PAnsiChar; uSize: UINT): UINT; stdcall; external kernel32 name 'GetSystemWindowsDirectoryA';

function GetSystemWindowsDirectory: string;
var
  buf: array[0..MAX_PATH] of Char;
  resultLength: Cardinal;
begin
  resultLength := GetSystemWindowsDirectoryA(@buf, SizeOf(buf));
  if resultLength = 0 then
    RaiseLastOSError;
  SetLength(Result, resultLength);
  Move(buf, PChar(Result)^, resultLength);
end;

How to get Windows path using Qt/C++

6 Answers6