为什么字符范围类 [A-z] 匹配下划线? [英] Why does character range class [A-z] match underscore?

问题描述

在多种语言中尝试过，结果相同.

JavaScript 示例:

/[A-z]/.test("_");//=>真的/[A-z]/.test("0");//=>错误的/[A-z]/.test("-");//=>错误的/[A-z]/.test("A");//=>真的

为什么第一种情况不返回false?

解决方案

字符范围不是那么智能.它们基于 ASCII 码.查看 Ascii 表.大写A-Z和小写a-z范围之间存在特殊字符，即:

<预><代码>[\]^_`

所以，应该是 A-Za-z 而不是 A-z.

Tried this in many languages with same result.

JavaScript example:

/[A-z]/.test("_"); // => true
/[A-z]/.test("0"); // => false
/[A-z]/.test("-"); // => false
/[A-z]/.test("A"); // => true

Why is the first case not returing false?

解决方案

Character ranges are not that intelligent. They are based on ascii codes. Check out Ascii Table. There exist special characters between upper-case A-Z and lower-case a-z range, namely:

[
\
]
^
_
`

So, instead of A-z it should be A-Za-z.

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