label setText value is 0

[babygal]

spinbox reads value input by user. then the value is multiplied with float value .and
displayed as output in a label. but the value is 0(incorrect).

Code:

QDoubleSpinBox *myspinBox;
QLabel *labelText;
 
 
QObject::connect(myspinBox,SIGNAL(valueChanged(QString)),this,SLOT(setnewText(QString)));
 
void myDialog::setnewText(QString newinput)
{
    newinputvalue = newinput;
    multiplication();
 
}
 
void myDialog::multiplication()
{
    float floatnum ;
    float floatmultiplywith;
    bool ok;
 
    floatnum = newinputvalue .toFloat(&ok);
 
    QString newValue = QString::number(floatmultiplywith*floatnum );
    labelText->setText(newValue );
 
}

QDoubleSpinBox *myspinBox;
QLabel *labelText;


QObject::connect(myspinBox,SIGNAL(valueChanged(QString)),this,SLOT(setnewText(QString)));

void myDialog::setnewText(QString newinput)
{
    newinputvalue = newinput;
    multiplication();

}

void myDialog::multiplication()
{
    float floatnum ;
    float floatmultiplywith;
    bool ok;
    
    floatnum = newinputvalue .toFloat(&ok);
    
    QString newValue = QString::number(floatmultiplywith*floatnum );
    labelText->setText(newValue );

}

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[Lykurg]

floatmultiplywith is not defined (= 0 as default I guess...), and did you check if your conversion to float works?

[babygal]

floatmultiplywith is not defined (= 0 as default I guess...), and did you check if your conversion to float works?

Yes . floatmultiplywith is not defined.

I removed the line as below and the conversion is correct:

labelText->setSuffix(" slices");

labelText->setSuffix(" slices");

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So now after removing the line of code as above the labelText value is correct!

[ChrisW67]

What did you do to give floatmultiplywith a value?

You are using a QSpinBox (QDoubleSpinBox) which will give an int (or double) when value() is called regardless of the prefix or suffix settings. By grabbing the text() value you get a string including the prefix/suffix when you really want the value. Calling cleanText() would be closer but you still have to manually convert to int/double. In short, if you want a number don't ask for the value as a string.