Slots in LineEdit

[Misko]

Hi,

I'm trying to 'connect' the value of a QSlider to a LineEdit's setText, but it doesn't work. On compiling there are no errors, but the value doesn't get into LineEdit...
Here is the code i've used:
#include <QApplication>
#include <QSlider>
#include <QLineEdit>
int main(int argc, char* argv[])
{
QApplication app(argc, argv);
QSlider *sldValue = new QSlider(Qt::Horizontal);
QLineEdit *leValue = new QLineEdit;
QObject::connect(sldValue, SIGNAL(valueChanged(int)), leValue, SLOT(setText("Test")));
// i just use the text 'Test' for now; this doesn't work also
// the widgets are then added to a layout
return app.exec();
}
With this example i just want to put the text 'Test' into LineEdit when the slider has changed of value. Can't be that hard?

I'm keeping the example very short, because i want this time to get QT right (i've abanded QT many times because i find it very difficult to learn)

Thanx in advance,
Misko

[marcel]

Slots don't work that way.
The signature(the parameters) of the signal must match the signature of the slot( but a slot can have fewer parameters than the signal, since it can ignore the extra ones).

You will eventually need to create a class for the main window and add a slot in your class( the following is the implementation of the slot):

void SomeClass::updateTextEdit(int value)
{
 QString str = QString("%1").arg(value);
 leValue.setText(str);
}

void SomeClass::updateTextEdit(int value)
{
 QString str = QString("%1").arg(value);
 leValue.setText(str);
}

To copy to clipboard, switch view to plain text mode 

The line edit and the slider should be members in your class.
Then, you can connect like:

connect(sldValue, SIGNAL(valueChanged(int)), this, SLOT(updateTextEdit(int)));

connect(sldValue, SIGNAL(valueChanged(int)), this, SLOT(updateTextEdit(int)));

To copy to clipboard, switch view to plain text mode 

This is pretty similar of what you want to do. It will set the current value of the slider in the line edit.

Regards

[Misko]

Hi Marcel,

Thx for your advice!
It took me some time to implement the class, because i'm still totally newbie with creating classes, but now it works!!!
1 question: in your reply you've put leValue.setText(str);
It gave me the error: request for member 'setText' in leValue, which is of non-class type 'QLineEdit'
Instead i've put leValue->setText(str); and it works, but don't ask me why?

Regards,
Misko

[marcel]

It works because leValue is a pointer.
I probably typed "." by mistake.

As a rule, remember that whenever you have a pointer to an object you can access its members with "->", as opposed to when you have the object allocated on the stack and you access them with "."( member selection by reference).

Regards