Variable can't get a value

[Gluon666]

So, I have this:

double A, B, C;

In my Window.h file and also some QComboBoxes and some QDoubleSpinBoxes like this:

QDoubleSpinBox *a;
QDoubleSpinBox *b;
QDoubleSpinBox *c; 
QComboBox *o1;
QComboBox *o2;
QComboBox *o3;

Then I use them like this:

if(o1->currentData(o1->currentIndex()) == 0)
    {
        A = a->value();
    }
    else if(o1->currentData(o1->currentIndex()) == 1)
    {
        A = a->value();
        A *= -1;
    }

    if(o2->currentData(o2->currentIndex()) == 0)
    {
        B = b->value();
    }
    else if(o2->currentData(o2->currentIndex()) == 1)
    {
        B = b->value();
        B *= -1;
    }

    if(o3->currentData(o3->currentIndex()) == 0)
    {
        C = c->value();
    }
    else if(o3->currentData(o3->currentIndex()) == 1)
    {
        C = c->value();
        C *= -1;
    }

(each QComboBox has 2 items, "+" and "-") but the A, B, C are always equal to 0, and I cannot figure out why.

Could you help me? Thanks in advance.

[Stoyan]

@Gluon666
Definition of function currentData is:

QVariant currentData(int role = Qt::UserRole) const

So it take as an argument role and not index.
May be you should use

if(o1->currentData() == 0)

or

if(o1->currentIndex() == 0)

instead both at the same time.

[Gluon666]

I tried but still, A, B and C are equal to 0:

if(o1->currentIndex() == 0)
    {
        A = a->value();
    }
    else if(o1->currentIndex() == 1)
    {
        A = a->value() * -1;
    }

I also tried with:

if(o1->itemData(o1->currentIndex()) == 0)
    {
        A = a->value();
    }
    else if(o1->itemData(o1->currentIndex()) == 1)
    {
        A = a->value() * -1;
    }

But yeah, no better results...

Mayhaps, I thought that it could be the slot that I use that is not working properly:

delta = ((B * B) - (4 * (A * C)));

    if(delta > 0)
    {
        S1 = ((-B) + sqrt(delta) / (2 * A));
        S2 = ((-B) - sqrt(delta) / (2 * A));

        msg += "S = { ";
        msg += QString::number(S1);
        msg += " ; ";
        msg += QString::number(S2);
        msg += " }";
    }
    else if(delta == 0)
    {
        S = (-B / (2 * A));

        msg += "S = { ";
        msg += QString::number(S);
        msg += " }";
    }
    else if(delta < 0)
    {
        msg = "Impossible";
    }

    QObject::connect(calculate, SIGNAL(clicked(bool)), this, SLOT(displayMsg()));
}

void Window::displayMsg()
{
    output->setText(msg);
}

This is the actual code (you probably recognized an equation solver) and mybe its the msg that is corrupted or something. No errors while debbugging, though

[Stoyan]

@Gluon666
How do you know that A, B and C are equal to 0? If they are, then your program will give error when you click on "calculate" - "Division by zero".
Could you put some debug statements in your code?
Like this:

qDebug() << "A: " << A << "\tB: " << B << "\tC: " << C;
delta = ((B * B) - (4 * (A * C)));