qCeil 向上取整
qFloor 向下取整
qRound 四舍五入
1 double a = 11.2;
2 double b = 11.5;
3 double c = -11.2;
4 double d = -11.5;
5
6 qDebug() << " " << ceil(a) << " " << ceil(b) << " " << ceil(c) << " " << ceil(d);
7 qDebug() << " " << floor(a) << " " << floor(b) << " " << floor(c) << " " << floor(d);
输出为：
12 12 -11 -11
11 11 -12 -12