小数处理

//保留两位小数，四舍五入 CGFloat rounded_up = round(0.355 * 100) / 100; NSLog(@"%.2lf",rounded_up);
//保留两位小数，直接进1(天花板函数) CGFloat rounded_up1 = ceilf(0.355 * 100) / 100; NSLog(@"%.2lf",rounded_up1);
//保留两位小数，舍弃后面所有位数。(地板函数) CGFloat rounded_up2 = floor(0.355 * 100) / 100; NSLog(@"%.2lf",rounded_up2);