How to read registry entries

[Abc]

I am calling an application built in C# from my Qt application. In the C# application I have some registry entires made. I want to read these entries in my Qt program and display certain messages depending on the value obtained. Please let me know how to do this.

[jpn]

See QSettings. Notice especially "Accessing the Windows Registry Directly" in the detailed description.

[Abc]

I read about QSettings but I am still not able to do it.
Can you please give a little more explanation about doing the same??

[santhoshv84]

Hi,

Use QSettings like this..

QSettings settings;
//setValue is to set the value to the registry.
settings.setValue("somekey", ui.someButton->isChecked() );

//value is to get the stored value from the registry..
settings.value("somekey", true).toBool();

All the best..

[patrik08]

search getGSDefaultExeName on file
http://fop-miniscribus.googlecode.co...tpanelmime.cpp
is part from http://www.qtcentre.org/forum/f-qt-p...=qtextdocument
a small qtextedit display on paper format like word openoffice..


here a small example to search on regedit on this case it search GhostScript by version....

/* find gpl GhostScript path or exe */
QString getGSDefaultExeName()
{
	QString gsName;
	QString gVersion;
#if defined Q_WS_WIN
	QFileInfo Pinfo;
	// Try to locate GhostScript thanks to the qsetting
	gsName = "gswin32c.exe";
	QSettings softs("HKEY_LOCAL_MACHINE\\Software",QSettings::NativeFormat);
	QStringList allsoftware = softs.childGroups();
	QStringList gsonly = allsoftware.filter(QRegExp("Ghostscript"));
	//////////qDebug() << "### gsonly " <<  gsonly;
	for (int i = 0; i < gsonly.size(); ++i)
	{
		const QString RealName = gsonly.at(i);  /* realpath */
		if (RealName.contains("Ghostscript"))
		{
			//////////qDebug() << "### soft " <<  RealName;
			for (int e=1;e<99;e++)
			{
				/* check version 8 ++ 99 down */
				gVersion = QString("8.%1").arg(100 - e);
				if (softs.value(RealName+"/"+gVersion+"/GS_DLL").toString().size() > 6)
				{
					Pinfo.setFile(softs.value(RealName+"/"+gVersion+"/GS_DLL").toString());
					return gsName.prepend(Pinfo.absolutePath()+"/");
				}
				/* check version 7 ++ 99 down */
				gVersion = QString("7.%1").arg(100 - e);
				if (softs.value(RealName+"/"+gVersion+"/GS_DLL").toString().size() > 6)
				{
					Pinfo.setFile(softs.value(RealName+"/"+gVersion+"/GS_DLL").toString());
					return gsName.prepend(Pinfo.absolutePath()+"/");
				}
			}
		}
	}
 
	/* win not having GPL Ghostscript ! */
	gsName = "";
	return gsName;
#endif

/* find gpl GhostScript path or exe */
QString getGSDefaultExeName()
{
	QString gsName;
	QString gVersion;
#if defined Q_WS_WIN
	QFileInfo Pinfo;
	// Try to locate GhostScript thanks to the qsetting
	gsName = "gswin32c.exe";
	QSettings softs("HKEY_LOCAL_MACHINE\\Software",QSettings::NativeFormat);
	QStringList allsoftware = softs.childGroups();
	QStringList gsonly = allsoftware.filter(QRegExp("Ghostscript"));
	//////////qDebug() << "### gsonly " <<  gsonly;
	for (int i = 0; i < gsonly.size(); ++i)
	{
		const QString RealName = gsonly.at(i);  /* realpath */
		if (RealName.contains("Ghostscript"))
		{
			//////////qDebug() << "### soft " <<  RealName;
			for (int e=1;e<99;e++)
			{
				/* check version 8 ++ 99 down */
				gVersion = QString("8.%1").arg(100 - e);
				if (softs.value(RealName+"/"+gVersion+"/GS_DLL").toString().size() > 6)
				{
					Pinfo.setFile(softs.value(RealName+"/"+gVersion+"/GS_DLL").toString());
					return gsName.prepend(Pinfo.absolutePath()+"/");
				}
				/* check version 7 ++ 99 down */
				gVersion = QString("7.%1").arg(100 - e);
				if (softs.value(RealName+"/"+gVersion+"/GS_DLL").toString().size() > 6)
				{
					Pinfo.setFile(softs.value(RealName+"/"+gVersion+"/GS_DLL").toString());
					return gsName.prepend(Pinfo.absolutePath()+"/");
				}
			}
		}
	}

	/* win not having GPL Ghostscript ! */
	gsName = "";
	return gsName;
#endif

To copy to clipboard, switch view to plain text mode 

[Abc]

I understood about QSettings but still not getting what I intend.

I have a key named 'Status' which can take two values 'success' or 'failed' according to the process and is available in the path 'Software/Burn'. I want to display some message depending on the value obtained. I have done it like...

QSettings settings("HKEY_CURRENT_USER/Software/Burn", QSettings::NativeFormat);
QString value = settings.value("HKEY_CURRENT_USER/Software/Burn/Status").toString();
if(value == "failed") {
	// display some message
} else if(value == "success") {
	// display some message
}

QSettings settings("HKEY_CURRENT_USER/Software/Burn", QSettings::NativeFormat);
QString value = settings.value("HKEY_CURRENT_USER/Software/Burn/Status").toString();
if(value == "failed") {
	// display some message
} else if(value == "success") {
	// display some message
}

To copy to clipboard, switch view to plain text mode 

Please let me know what's wrong in this, why doesn't it work???

[jpn]

Please follow the example in the docs. Your attempt is radically different. Notice what docs say about slashes and about registry entries appearing under the specified path.

[Abc]

Still does not work for me...

Did u mean that I should do something like...

QSettings settings("HKEY_CURRENT_USER\\Software\\Burn", QSettings::NativeFormat);
QString value = settings.value("Status").toString();
if(value == "failed") {
	// display some message
} else if(value == "success") {
       // display some other message
}

QSettings settings("HKEY_CURRENT_USER\\Software\\Burn", QSettings::NativeFormat);
QString value = settings.value("Status").toString();
if(value == "failed") {
	// display some message
} else if(value == "success") {
       // display some other message
}

To copy to clipboard, switch view to plain text mode 

Please tell me what's going wrong now.

[jpn]

Could you export and paste contents of HKEY_CURRENT_USER\\Software\\Burn?

[Abc]

The contents are as follows...

(Default) REG_SZ (value not set)
Status REG_SZ failed
CommPort REG_DWORD 0x00000003(3)
CommSpeed REG_DWORD 0x00000000(0)
FileName REG_SZ C:/Documnets & Settings/.... (path to the file)

[jpn]

Is that really an export? As far as I remember it looks a bit different. I wanted to assure that the path is actually correct but I guess you've already done that. Anyway, what does

qDebug() << settings.childKeys();
qDebug() << settings.childGroups();

qDebug() << settings.childKeys();
qDebug() << settings.childGroups();

To copy to clipboard, switch view to plain text mode 

output?

[Abc]

These two commands don't return any value...
Now, how to proceed.

[jpn]

So are you 100% sure that the registry path is correct? Does this assert?

QSettings settings("HKEY_CURRENT_USER", QSettings::NativeFormat);
Q_ASSERT_X(settings.childGroups().contains("Software"), "Software", "Software doesn't exist");
settings.beginGroup("Software");
 
Q_ASSERT_X(settings.childGroups().contains("Burn"), "Burn", "Burn doesn't exist");
settings.beginGroup("Burn");
 
Q_ASSERT_X(!settings.allKeys().isEmpty(), "Keys", "Software/Burn is empty");
qDebug() << settings.allKeys();

QSettings settings("HKEY_CURRENT_USER", QSettings::NativeFormat);
Q_ASSERT_X(settings.childGroups().contains("Software"), "Software", "Software doesn't exist");
settings.beginGroup("Software");

Q_ASSERT_X(settings.childGroups().contains("Burn"), "Burn", "Burn doesn't exist");
settings.beginGroup("Burn");

Q_ASSERT_X(!settings.allKeys().isEmpty(), "Keys", "Software/Burn is empty");
qDebug() << settings.allKeys();

To copy to clipboard, switch view to plain text mode 

[Abc]

If I include this snippet, I don't get any output.
Infact, qDebug does not work for me I guess.

Just don't know how to get this working...

[jpn]

You could have said that earlier when I asked for the output of childKeys() and childGroups(). In case you're using an IDE of some kind, check its output console. In case you're not, enable console by adding

CONFIG += debug console

CONFIG += debug console

To copy to clipboard, switch view to plain text mode 

to the .pro file, re-run qmake, make clean and recompile the application. Now you should see some output in the console window.

[Abc]

If I include this in the .pro file, the application does not build.

I am writing Qt code in notepad++ and using Qt 4.4.0 Command Prompt to build my application.

I did this... added the given line to .pro file, did a make clean and then qmake followed by a make.
The error message reads like...
C:\MinGW\bin\..\lib\gcc\ming32\3.4.5\..\..\..\..\m ingw32\bin\ld.exe: cannot find -lQtGuid4
collect2: ld returned 1 exit status
mingw32-make[1]: *** [debug\myApplication.exe] Error 1
mingw32-make[1]: Leaving directory '<path to the directory>'
mingw32-make: *** [debug] Error 2

[jacek]

You don't have Qt libraries built in debug mode. There should be a "Build Qt in debug mode" or similar link in start menu.