parseFloat字符串长度超过16个字符 [英] parseFloat of string longer than 16 characters

问题描述

字符串的parseFloat是否限制该字符串可以包含多少个字符?我在这里看不到有关限制的任何内容: https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/parseFloat

Does parseFloat of a string have a limit to how many characters the string can be? I don't see anything about a limit here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseFloat

但是在控制台中运行以下内容似乎会显示出我意料之外的结果.

But running the following in console seems to show results I wasn't expecting.

parseFloat('1111111111111111'); // 16 characters long
// result 1111111111111111

parseFloat('11111111111111111'); // 17 characters long
// result 11111111111111112

任何人都可以帮我分解一下吗?

Can anyone break this down for me?

推荐答案

在Javascript中，浮点数存储为双精度值.这些数字大约有16位有效数字，这意味着不一定要准确地存储17位数字.

In Javascript, floating point numbers are stored as double precision values. These have about 16 significant digits, which means that a 17-digit number won't necessarily be stored exactly.

您可以为parseFloat()提供任意长度的数字，但不能存储大于1.79769× 10 ³⁰⁸ 的任何数字，这是可以存储的最大值在双精度变量中.

You can supply numbers of any length to parseFloat(), but it won't be possible to store anything larger than 1.79769×10³⁰⁸, which is the largest possible value that can be stored in a double precision variable.

如果有时间，我建议您阅读以下内容:什么每个计算机科学家都应该了解浮点算法

I'd recommend reading this if you have time: What Every Computer Scientist Should Know About Floating-Point Arithmetic

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