How to communicate with external programs?

[deekayt]

Forked from: http://www.qtcentre.org/forum/f-qt-d...-qt4-4108.html

THANK YOU VERY MUCH
I WAS ABLE TO RUN THE APPLICATION ATLAST ....

I need to first start some processes fromthe mother application ( dialog) on the clickof the pushbutton. I tried the Q process but it didnot work out.Then I resorted to System call . This I know is not a clean process but just to check the slot thing I have put this now.

my code snippet is as

steg::steg(QWidget *parent)
: QDialog(parent)
{
ui.setupUi(this);
connect(ui.okButton, SIGNAL(clicked()), this, SLOT(test()));
connect(ui.cancelButton, SIGNAL(clicked()), this, SLOT(open_file()));
}

void steg::test()
{
system("e:\"\"\"stego.jpg");
}

you see above the okbutton on being clicked gives signal to slot test() .test() function has system call to launch picture viewer to show the file stego.jpg.
Canyou suggest a better method to do this task.

Secondly I need to create , open , write , execute and close the file very often in my program on the click of buttons.

i tried the following snippets

void steg::writeinfile()
{
char eog_comand[]= "eog";
char space[]= " ";
FILE *fp;
fp = fopen ("e:\"\"\"trial.txt", "w+");
fputs (eog_comand,fp);
fputs (space,fp);
fclose(fp);
}

this is simple c code .But when i run the program it crashes.
I tried Qfile commands

void steg::writeinfile()
{
QFile file;
file.setFileName("e:\"\"\"trial.txt");
file.open(QIODevice::WriteOnly);
file.write(msg, qstrlen(msg)); // write to stderr
file.close();
}

But that alsodoesnot work
Someguidance please.