Encoding problems with the arguments of a Qt application under windows 7

stephane78

Hi,
I use the class SingleApplication for my purpose in a Qt software under windows:

SingleApplication(int &argc, char *argv[], const QString uniqueKey);  

......
SingleApplication::SingleApplication(int &argc, char *argv[], const QString uniqueKey) : QApplication(argc, argv)

In my main.cpp :

SingleApplication app(argc, argv,"Mysoftware");
 if (app.alreadyExists())
        {
            QString filename ;
            
            if(argc>1)
            {
                int nfichiers=argc-1;
                int l=0;
                while(l<nfichiers)
                {
                    //filename=argv[l+1];

                    filename=QString::fromUtf8(argv[l+1]);

I have added an entry in the contextual menu of windows (in the registry) that calls mysoftware with a selected file as argument : mysoftware %1
if I select a file with special characters (é,è,à, because I have a french keyboard and a french windows 7) it doesn't run well and I have an encoding problem.
If replace QString::fromUtf8 by QString::fromLatin1 or QString::fromLocal8Bit it crashes the software with files with special characters (haven't already debugged that).
What is the encoding of the explorer on a french windows 7 ?
I have tried several things like :

QTextCodec *codec = QTextCodec::codecForName("System");
    QTextCodec::setCodecForLocale(codec);
filename=QString::fromLocal8Bit(argv[l+1]);

but nothing works.
has someone an idea ?

SGaist

Hi,

Are you sure you need to do that conversion ? What do you get if you print the value of your arguments ?

By the way, there's the QtSingleApplication class from the QtSolution module that is a cross-plaform single instance application handler.

stephane78

@SGaist, Ok thank you I will perhaps later try with QtSingleApplication of QtSolution instead of SIngleApplication.
If I print the first arguments I must transform the char *, argv[1] into a QString to display it in a qmessagebox .if I do
QString cs=argv[1]; (which is the same as cs=QString::fromUtf8(argv[1])) and then QMessageBox ..., there is an encoding problem...
and even if I use QtSingleApplication, I must do that, i.e. transmit the arguments (char *) to a QString...
so I think windows is unicode and transmit wide char to the Qt program but the Qt program take char * as parameters...

stephane78

Hi Sgaist, OK you have had a good idea with the message box.so there was probably two problems : if I want to display the right string in the messagebox I must do :

QTextCodec *codec = QTextCodec::codecForName("System");
    QTextCodec::setCodecForLocale(codec);
QString cs=codec->toUnicode(argv[1]);
			QMessageBox::information(NULL,"arg 1",cs);

so I will use the three first lines now...
and there must be another problem with my class SingleApplication and now I will try to use the last version of QtSingleApplication instead of this class.
I will come back here when it works...

stephane78

@SGaist , ok my problem is solved now thanks to these three lines and thanks to the class QtSingleApplication of Qtsolutions.
If I use a french windows it takes the special french characters (é,è,à) in the name of selected files ,through the contextual menu of windows .

Solved Encoding problems with the arguments of a Qt application under windows 7