Getting the value from a spinbox

[jpn]

Add a new slot, for example Window::calculate(). Connect both spin boxes to that slot:

connect(valueSpinBoxJ1,SIGNAL(valueChanged(int)),this,SLOT(calculate()));
connect(valueSpinBoxJ2,SIGNAL(valueChanged(int)),lcd2,SLOT(calculate()));

connect(valueSpinBoxJ1,SIGNAL(valueChanged(int)),this,SLOT(calculate()));
connect(valueSpinBoxJ2,SIGNAL(valueChanged(int)),lcd2,SLOT(calculate()));

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In the slot, retrieve values and add them together:

void Window::calculate()
{
	int valJ1 = valueSpinBoxJ1->value();
	int valJ2 = valueSpinBoxJ2->value();
	lcd3->display(valJ1 + valJ2);
}

void Window::calculate()
{
	int valJ1 = valueSpinBoxJ1->value();
	int valJ2 = valueSpinBoxJ2->value();
	lcd3->display(valJ1 + valJ2);
}

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[X-man]

Thanks JPN. So, I added "void calculate();" under the public slots inside window.h.

I then added the two connections (with the correction of "lcd2" to "this", I assumed), under my "Window::Window()" inside the window.cpp and added at the end the "void Window::calculate() {.....}"

First time run, it crashed - something not working with QLCDNumber.h it said. I changed that and instead of sending the value to an LCD, I used

qDebug("Val12 = %.4f", valJ1+valJ2)

qDebug("Val12 = %.4f", valJ1+valJ2)

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to check what's going on...

In the debug window, I do get "Val12 = 0". The good part is that "Val12 = 0" reappears everytime I change something in the two spinboxes. The sad part is that it just doesn't have the correct value - stays zero. I suppose that "calculate" is done every time I change something in one of the two spinboxes, the valueChanged connection works OK, but valJ1 and valJ2 don't get the value of their spinbox from the valueSpinBoxJ1/2->value thing... which is not good at all... how can that be?

WHAT'S WRONG!?!?!?!

X-man

[jpn]

Oh yes, "lcd2" was a typo, sorry. There's at least a classical mix up with local and member variables. You have declared a member variable:

QLCDNumber *lcdX;

QLCDNumber *lcdX;

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But you are assigning to a local variable:

QLCDNumber *lcdX = new QLCDNumber(X);

QLCDNumber *lcdX = new QLCDNumber(X);

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Now if you try to dereference it in another function:

ldcX->something();

ldcX->something();

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You'll get a crash because you are using an uninitialized pointer. So you should make it:

lcdX = new QLCDNumber(X);

lcdX = new QLCDNumber(X);

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[X-man]

Right on, JPN, about my mistake on the local/member variables - that is now corrected.

So, I am now using:

void Window::calculate()
{
	int valJ1 = valueSpinBoxJ1->value();
	int valJ2 = valueSpinBoxJ2->value();
	int X = valJ1+valJ2;
    lcd3->display(X);
	qDebug("X = %.4f",X);
}

void Window::calculate()
{
	int valJ1 = valueSpinBoxJ1->value();
	int valJ2 = valueSpinBoxJ2->value();
	int X = valJ1+valJ2;
    lcd3->display(X);
	qDebug("X = %.4f",X);
}

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lcd3 is working (obviously), but I still get consecutively "X=0.0000". My worry is that if I need to use X somewhere else, it will not be there with the correct value - how should I deal with that?

Thanks for your help so far though!

X-man

[vonCZ]

whatup X-

try:

qDebug("X = %d",X);

qDebug("X = %d",X);

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your "X" variable is an int

[jpn]

With

qDebug() << X;

qDebug() << X;

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there would be no such problem..

[X-man]

You are both right - i accidentally fixed when I turner all the v's to floats. So now everything works like a charm...

...till everything stops working again.

Thanks for your replies, (unfortunately) I will get back with more questions

X-man