正则表达式[A-z]和[a-zA-Z]之间的区别 [英] Difference between regex [A-z] and [a-zA-Z]

问题描述

我正在使用正则表达式为一个文本框编写输入验证器，我只想要字母字符。我想知道 [Az] 和 [a-zA-Z] 是否相同或者是否有明显的差异表现。

I am using a regex to program an input validator for a text box where I only want alphabetical characters. I was wondering if [A-z] and [a-zA-Z] were equivalent or if there were differences performance wise.

我在搜索中继续阅读 [a-zA-Z] ，并且没有提及 [Az] 。

I keep reading [a-zA-Z] on my searches and no mention of [A-z].

我正在使用java的 String.matches（正则表达式）。

I am using java's String.matches(regex).

推荐答案

[Az] 将匹配范围内的ASCII字符从 A 到 z ，而 [a-zA-Z] 将匹配范围从 A 到 Z 和范围内的ASCII字符从 a 到 z 。乍一看，这似乎相当 - 但是，如果你看一下ASCII字符的这个表，你会看到 Az 包含其他几个字符。具体来说，它们是 [， \ ，] ， ^ ， _ ，`（你明显不知道）不想要。）

[A-z] will match ASCII characters in the range from A to z, while [a-zA-Z] will match ASCII characters in the range from A to Z and in the range from a to z. At first glance, this might seem equivalent -- however, if you look at this table of ASCII characters, you'll see that A-z includes several other characters. Specifically, they are [, \, ], ^, _, and ` (which you clearly don't want).

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