Displaying Integers on QLabels?

问题

Basically i'm making a simple calculator program to understand the basics of C++ GUI however I get an error message leading to the line of code I have in the void MainWindow::addx() to label -> setText(c); with an error message of:

invalid user-defined conversion from 'int' to 'const QString&'[-fpermissive]

I really don't know what that error message means I assume it means I cant display an integer on a label. I just wanted to know if I am able to display an integer on my label or do I have to use a different widget.

class MainWindow() {
   int a, b, c;
   QLabel * label;
   ...
};

void MainWindow::addx()
    c = a + b;
    label -> setText(c);
}

回答1:

You have to convert it:

firstnumberx();
secondnumberx();
c = a+b;
label->setText(QString::number(c));

回答2:

This should work..

label -> setText(QString::number(c));

If you need to add multiple number inside some string you can try below..

label -> setText(QString("%1").arg(c));

回答3:

QLabel has setNum() methods taking int or double arguments:

label->setNum(c);

The setNum() methods format the supplied number and then set the text property with the formatted value. The documentation does not specify which locale is used for formatting, so you may wish to experiment.

来源：https://stackoverflow.com/questions/21218427/displaying-integers-on-qlabels