目标c中有一个数字的浮点数是否有简单的方法？ [英] Is there any easy way to round a float with one digit number in objective c?

问题描述

是。你是对的。当然这是一个重复的问题。在标记我的问题之前，请继续阅读下面的内容。

我想将一个float值，即

  56.6748939至56.7 
 56.45678至56.5 
 56.234589至56.2 
  

实际上它可以是任意数量的小数精度。但我想把它凑到最近的价值。 （如果它大于或等于5，则循环，如果不是，则循环下去）。

我可以用下面的代码。
$ b $ pre $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $ $
[numberFormatter setMaximumFractionDigits：1];
[numberFormatter setRoundingMode：NSNumberFormatterRoundUp];

NSString * roundedString = [numberFormatter stringFromNumber：[NSNumber numberWithFloat：value]];
NSNumber * roundedNumber = [NSNumber numberFromString：roundedString];
float roundedValue = [roundedNumber floatValue];

上面的代码看起来像一个漫长的过程。我有几个数字四舍五入。 所以这个过程很难将浮点值转换成NSNumber和NSString，并转换成NSNumber并浮动。

有没有其他简单的方法实现我所问的？

我仍然怀疑上面的代码。它说 roundUp 。所以当谈到 roundDown 时，它会起作用吗？

解决方案

你只需乘以10，然后除以10？

Yes. You are right. Of Course this is a duplicate question. Before flag my question, please continue reading below.

I want to round a float value, which is

56.6748939 to 56.7
56.45678 to 56.5
56.234589 to 56.2

Actually it can be any number of decimal precisions. But I want to round it to nearest value. (If it is greater than or equal to 5, then round up and if not, then round down).

I can do that with the below code.

float value = 56.68899
NSNumberFormatter *numberFormatter = [[NSNumberFormatter alloc]init];
[numberFormatter setMaximumFractionDigits:1];
[numberFormatter setRoundingMode:NSNumberFormatterRoundUp];

NSString *roundedString = [numberFormatter stringFromNumber:[NSNumber numberWithFloat:value]];
NSNumber *roundedNumber = [NSNumber numberFromString:roundedString];
float roundedValue = [roundedNumber floatValue];

Above code looks like a long process. I have several numbers to round off. So this process is hard to convert a float value into NSNumber and to NSString and to NSNumber and to float.

Is there any other easy way to achieve what I asked ?

I still have a doubt in the above code. It says roundUp. So when it comes to roundDown, will it work?

解决方案

Can't you simply multiply by 10, round the number, then divide by 10?

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