Will I learn to implement custom SIGNALS?

[fatecasino]

Reading examples and documentation I start to believe that making a custom SIGNAL is not a difficult task. Trying to do it though I realize that I cannot do it!!

Here's a simple example, that if I understand it I will be able to make more custom signals.

1. a line edit for number A
2. a line edit for number B
3. a line edit to present the result of the Multiplication

Here is the corresponding code:

MyDialog::MyDialog(QWidget *parent)
    : QWidget(parent)
{
 
    QLineEdit *numberA = new QLineEdit;
    QLineEdit *numberB  = new QLineEdit;
 
    result  = new QLineEdit;
 
    numberA->setText("1.0");
    numberB->setText("1.0");
    result->setText("1.0");
 
 
 
    vboxlayout = new QVBoxLayout(this);
    vboxlayout->addWidget(numberA);
    vboxlayout->addWidget(new QLabel("x"));
    vboxlayout->addWidget(numberB);
    vboxlayout->addWidget(new QLabel("="));
    vboxlayout->addWidget(result);
 
    setLayout(vboxlayout);
}
 
 
void MyDialog::showMultiplication(QString Astring,QString Bstring)
{
    double A,B,Res;
    QString ResString;
 
 
    A= Astring.toDouble();
    B= Bstring.toDouble();
 
 
    Res = A*B;
 
    ResString.setNum(Res);
 
    result->setText(ResString);
}

MyDialog::MyDialog(QWidget *parent)
    : QWidget(parent)
{

    QLineEdit *numberA = new QLineEdit;
    QLineEdit *numberB  = new QLineEdit;

    result  = new QLineEdit;

    numberA->setText("1.0");
    numberB->setText("1.0");
    result->setText("1.0");



    vboxlayout = new QVBoxLayout(this);
    vboxlayout->addWidget(numberA);
    vboxlayout->addWidget(new QLabel("x"));
    vboxlayout->addWidget(numberB);
    vboxlayout->addWidget(new QLabel("="));
    vboxlayout->addWidget(result);

    setLayout(vboxlayout);
}


void MyDialog::showMultiplication(QString Astring,QString Bstring)
{
    double A,B,Res;
    QString ResString;


    A= Astring.toDouble();
    B= Bstring.toDouble();


    Res = A*B;

    ResString.setNum(Res);

    result->setText(ResString);
}

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QUESTION:
When the user inserts a new number (anywhere A or B) the multiplication result should be shown directly in the result line edit. The SLOT is obliously the showMultiplication(QString Astring,QString Bstring).

The SIGNAL should be something like
sendNewNumbersForMultiplication(QString ,QString )

BUT, I really cannot understand how to implement it!!
Any help?

[pan]

Maybe I miss-understand you?

But don't you just want to declare a signal in your header file. Then emit that signal when you get a signal (whichever you choose) from the Line edit object?

Like in your header:

signals:
void sendNewNumbersForMultiplication(QString ,QString );

signals:
void sendNewNumbersForMultiplication(QString ,QString );

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Is this what you are trying to do?

[fatecasino]

yes, of course, I am trying to make the scenario described above to work. The user writes in a number and the system writes automatically the multiplication result in the result line edit.
The declaration of the SIGNAL will then be as you said:

signals:
void sendNewNumbersForMultiplication(QString ,QString );

signals:
void sendNewNumbersForMultiplication(QString ,QString );

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But, what will I write into the implementation of the function in the .cpp file?

void MyDialog::sendNewNumbersForMultiplication(QString ,QString )
{
 
??
 
}

void MyDialog::sendNewNumbersForMultiplication(QString ,QString )
{

??

}

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