QT: Float to QString

Question

I am new to QT. I am facing some strange problem in floating point values. The following code displays a message box WITH decimal points. ie, 10.53

QMessageBox Msgbox;
float num = 10.53;
QString str = QString::number(num, 'g', 4);
Msgbox.setText(str);
Msgbox.exec();

Where as the following code displays a message box WITHOUT decimal points. ie, 1

QMessageBox Msgbox;
float num = 120/77;
QString str = QString::number(num, 'g', 4);
Msgbox.setText(str);
Msgbox.exec();

Why the digits after the decimal point are ignored in the second code snippet? I changed the data type to double and qreal. Nothing worked.

Answer 1

because 120/77 is dividing 2 integers (resulting in a integer) and then converting to float

you need to convert the numbers to float before dividing

float a = 120, b = 77;
float num = a/b;

Answer 2

adding (float) before the numbers solved the issue. ie, float num = (float)120/77;

Answer 3

float num = 120.0/77.0;

也可以，对于C来说是标准的。