# Rounding up numbers

• Hi,

I have been trying to round up some numbers but I cannot figure it out. What I have is a little program that when a button is clicked it gets information form 7 input fields and then it makes the following calculations.

@void MainWindow::on_pushButton_Calculate_clicked()
{
// input fields
QString partW = ui->lineEdit_PartWidth->text();
QString partL = ui->lineEdit_PartLength->text();
QString sheetW = ui->doubleSpinBox_SheetWidth->text();
QString sheetL = ui->doubleSpinBox_SheetLength->text();
QString clamp = ui->doubleSpinBox_Clamp->text();
QString kerf = ui->doubleSpinBox_Kerf->text();
QString web = ui->doubleSpinBox_Web->text();

``````//converting inputs to numbers and adding some other factors
partWidth = partW.toFloat() + kerf.toFloat();
partLength = partL.toFloat() + kerf.toFloat();
sheetLength = sheetL.toFloat() - (web.toFloat()* 2);
sheetWidth = sheetW.toFloat() - (clamp.toFloat() - .5);

partsY = sheetWidth / partWidth;
partsX = sheetLength /partLength ;

totalParts = partsY * partsX;

ui->label_TotalParts->setText(QString::number(totalParts));
``````

}@

Everything is working as it should the only thing is that I want to round up partsY and partsX so that when they are multiplied there are no decimal numbers.

I tried modifying the following line...
@totalParts = round(partsY) * round(partsX);@
but it doesn't work.

I know it may be hard to know whats wrong without seeing the actual code but can someone give it a shot?

Thanks a lot for your help.

• The rounding method is called "qRound":http://qt-project.org/doc/qt-4.8/qtglobal.html#qRound .

• I would suggest to round after the multiplication. That is more accurate. qRound is the way to go, so this should work:
@totalParts = qRound(partsY * partsX);@
If you don't want to use the QRound the basic way is to have a float value, add (positive value) or subtract 0,5 (negative value) and typeconvert into a int.
@if(partsY * partsX < 0)
iTotalParts = (int)((partsY * partsX) - 0,5);
else
iTotalParts = (int)((partsY * partsX) + 0,5);@

Greetz

• I was trying to use qRound when I realized that this could be just a metter of changing my variable type from float to int in fact it did the trick.

Thank you all very much for your help.

• Note that changing the variable type will not result in "natural" rounding. It will result in flooring values. So, 2.9999 will be "rounded" to 2, not 3.

• That is actually what I want. But thanks a lot for the clarification.

I love this forum!

Thanks a lot