How to find Application Data directory?

[Teuniz]

I want to save some program settings.
How do I know what the exact path is to "C:\Documents and Settings\user\Application Data" directory on windows?

[wysota]

You need to use WinAPI calls to get that or read appropriate values from Windows Registry (through QSettings), they are probably there somewhere...

[blue.death]

This is a possible solution (it's the same used in some Qt code):



#ifdef Q_WS_WIN
#include "qt_windows.h"
#include "qlibrary.h"
#ifndef CSIDL_COMMON_APPDATA
#define CSIDL_COMMON_APPDATA 0x0023 // All Users\Application Data
#endif
#ifndef CSIDL_APPDATA
#define CSIDL_APPDATA 0x001a // <username>\Application Data
#endif

QString MyClass::specialFolder(int type)
{
QString result;

QLibrary library(QLatin1String("shell32"));
QT_WA( {
typedef BOOL (WINAPI*GetSpecialFolderPath)(HWND, LPTSTR, int, BOOL);
GetSpecialFolderPath SHGetSpecialFolderPath = (GetSpecialFolderPath)library.resolve("SHGetSpecialFolderPathW");
if (SHGetSpecialFolderPath) {
TCHAR path[MAX_PATH];
SHGetSpecialFolderPath(0, path, type, FALSE);
result = QString::fromUtf16((ushort*)path);
}
} , {
typedef BOOL (WINAPI*GetSpecialFolderPath)(HWND, char*, int, BOOL);
GetSpecialFolderPath SHGetSpecialFolderPath = (GetSpecialFolderPath)library.resolve("SHGetSpecialFolderPathA");
if (SHGetSpecialFolderPath) {
char path[MAX_PATH];
SHGetSpecialFolderPath(0, path, type, FALSE);
result = QString::fromLocal8Bit(path);
}
} );

// Fallback on error
if (result.isEmpty()) {
switch (type) {
case CSIDL_COMMON_APPDATA:
result = QLatin1String("C:\\temp\\qt-common");
break;
case CSIDL_APPDATA:
result = QLatin1String("C:\\temp\\qt-user");
break;
default:
;
}
}

return result;
}


You could also use the Win32 API to look for the APPDATA environment variable or look in the registry for the appropriate keys (somewhere in Software\Microsoft\Windows\Current Version\...)

[Bagstone]

Hello first, although I'm reading quite a while on qtcentre.org, this is my first post! ;-)


I'd like to ask if this is really the only way?
I saved some settings for my application and now I thought about putting a log file there, but I want to limit it to a certain size (for example 1000 lines or even better a specific size like 50kb).

As the application directory isn't always writable for the current user, I thought it would be better to put it into the user's .config dir, or on windows, Application Data (language specific of course). Maybe I better use another folder or avoid the log file at all...


I'm just a bit uneasy about using this WINAPI thing and searching the registry and so on.
Additionally my project is a static binary to run on every PC without the need to ship the libraries with it and I don't know if this method might cause a problem to the static linker... but this is just a guess from a frightened programmer who experienced already too many problems ;-)

[Teuniz]

Additionally my project is a static binary to run on every PC without the need to ship the libraries with it and I don't know if this method might cause a problem to the static linker...

I can confirm that the above code from blue.death works fine with static linking.

[przemoc]

I want to save some program settings.
How do I know what the exact path is to "C:\Documents and Settings\user\Application Data" directory on windows?
Someday I asked myself similar question, but in platform independent way. My solution is not the prettiest one, but works.


// obtain (platform specific) application's data/settings directory
QSettings ini(QSettings::IniFormat, QSettings::UserScope,
QCoreApplication::organizationName(),
QCoreApplication::applicationName());
QString dir = QFileInfo(ini.fileName()).absolutePath();

dir string will contain:

on Windows - "%APPDATA%\<Organization Name>" ("<Drive>:\Documents and Settings\<login>\<Application Data>\<Organization Name>")
on Unix and Mac OS X - "$HOME/.config/<Organization Name>"

where <text> depends on your application & workspace (organization name, lingual version of Windows, etc.). This is a good place to put your data/settings without using QSettings.

[jonny.dee]

I know it's been a long time since this thread was created, but maybe my reply might still be useful for others.

You can also use QDesktopServices (http://doc.qt.nokia.com/latest/qdesktopservices.html) class to get the system paths.

Cheers,
Jonny

[milgner]

Another late update for anyone finding themselves here via Google or such:

This part of the QDesktopServices class has been replaced by QStandardPaths (http://qt-project.org/doc/qt-5.0/qtcore/qstandardpaths.html) in Qt 5.