NSString到双重问题 [英] NSString to Double Issue

问题描述

可能很简单，但我不明白......
我有一个NSString 50.81114 我希望将它转换为双... < br>
目前我正在使用 [string doubleValue] ，但这是 50.811140000002

发生了什么事？！

Probably really simple but I don't understand... I have an NSString 50.81114 and I want to convert it into a double...
Currently I am using [string doubleValue] but this is coming out as 50.811140000002
What's going on?!

Disco

推荐答案

Double （以及任何浮点数）都有自己的准确度限制，通常是15-16位左右。请注意，这不仅适用于Objective-C，而且适用于所有语言，因为二进制浮点显示的限制。

Double (and any floating point number) has its own limit of accuracy, normally it would be around 15-16 digits. Note this is not just for Objective-C, but for all the languages because of the limit of binary floating point presentation.

您显示的内容是正常的，因为 50.81114 无法以二进制形式准确显示，必须使用近似值。

What you show is just normal, since 50.81114 cannot be accurately presented in binary, approximation must be used.

您可以阅读维基百科供进一步阅读。

You can read Wikipedia for further reading.

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