正则表达式 [\w-] 是什么意思? [英] What does the regular expression [\w-] mean?

问题描述

我查看了文档，但找不到 [\w-] 的含义.谁能告诉我 [\w-] 在 Ruby 中是什么意思?

I checked the documentation, and cannot find what [\w-] means. Can anyone tell me what [\w-] means in Ruby?

推荐答案

方括号 [] 表示字符类.字符类将匹配其中的任何内容.

The square brackets [] denote a character class. A character class will match any of the things inside it.

\w 是一个特殊的类，称为单词字符".它是 [a-zA-Z0-9_] 的简写，所以它会匹配:

\w is a special class called "word characters". It is shorthand for [a-zA-Z0-9_], so it will match:

• a-z(全部小写)
• A-Z(全部大写)
• 0-9(所有数字)
• _(下划线)

• a-z (all lowercase letters)
• A-Z (all uppercase letters)
• 0-9 (all digits)
• _ (an underscore)

您所询问的类 [\w-] 是一个由 \w 和 - 组成的类.所以它将匹配上面的列表，加上连字符(-).

The class you are asking about, [\w-], is a class consisting of \w and -. So it will match the above list, plus hyphens (-).

正如所写的那样，[\w-]，这个正则表达式将匹配单个字符，只要它在上面的列表中，或者是一个破折号.

Exactly as written, [\w-], this regex would match a single character, as long as it's in the above list, or is a dash.

如果您要在末尾添加量词，例如[\w-]* 或 [\w-]+，那么它将匹配以下任何字符串:

If you were to add a quantifier to the end, e.g. [\w-]* or [\w-]+, then it would match any of these strings:

fooBar9
foo-Bar9
foo-Bar-9
-foo-Bar---9abc__34ab12d

它会部分匹配这些:

foo,Bar9                    # match 'foo' - the ',' stops the match
-foo-Bar---9*bc__34ab12d    # match '-foo-Bar---9', the '*' stops the match

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