abs, fabs, fabsf分别对应整形,float ,double
例如fabs(-0.856) = 0.856;
ios小数向上、下取整,计算结果向上、下取整:
小数向上取整,指小数部分直接进1 x=3.14,ceilf(x)=4
小数向下取整,指直接去掉小数部分 x=3.14,floor(x)=3
小数处理 四舍五入
NSLog(@”%f”,round(12345.6789));//12346.000000
NSLog(@”%f”,round(12345.6749*100)/100);//12345.670000
NSNumber *num = [NSNumber numberWithFloat:12.1250];
NSLog(@”%@”,[NSString stringWithFormat:@”%.2f”,round([num floatValue]*100)/100]);//12.13