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This article mainly shows you "what do regular expressions [\ s\ S] * and [\ w\ W] * mean". The content is easy to understand and clear, hoping to help you solve your doubts. Let the editor lead you to study and learn what regular expressions [\ s\ S] * and [\ w] * mean ".

Q:

For example, [amurz] represents any one from a to z.

Isn't that right? Who can explain to me all the uses of []? Thank you.

A:

It means full wildcard, and\ s refers to white space, including spaces, line breaks, tab indentation, etc., while\ s is just the opposite.

Such a positive and negative, it means that all the characters, complete, word-for-word.

In addition, the symbol [] indicates that the individual characters contained in it appear in any order, such as the following rule:

[ace] *

This means that whenever the three arbitrary letters a/c/e appear, they will be matched.

[\ s] indicates that whenever there is a blank, it will match.

[\ s] indicates that if it is not blank, it will match.

\ w matches any word characters that include underscores. Equivalent to "[A-Za-z0-9]".

\ W matches any non-word characters. Equivalent to "[^ A-Za-z0-9]".

Then their combination means that all of them match, and the corresponding ones are [\ w\ W], etc., which have exactly the same meaning.

Another point to say is why there is a "." This wildcard should be used in this way.

In fact, the usage of [\ s\ S] is compared with that of [\ w\ W]. There are more matches, because "." Line breaks are not matched, and people are used to using full wildcard modes such as [\ s\ S] or [\ w\ W] when there is a newline match.

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