re正则表达式13_review of regex symbols

Review of Regex Symbols

This chapter covered a lot of notation, so here’s a quick review of what you learned:

The

?

matches zero or one of the preceding group.

The

*

matches zero or more of the preceding group.

The

+

matches one or more of the preceding group.

The

{n}

matches exactly n of the preceding group.

The

{n,}

matches n or more of the preceding group.

The

{,m}

matches 0 to m of the preceding group.

The

{n,m}

matches at least n and at most m of the preceding group.

{n,m}?

or

*?

or

+?

performs a nongreedy match of the preceding group.

^spam

means the string must begin with spam.

spam$

means the string must end with spam.

The

.

matches any character, except newline characters.

\d

,

\w

, and

\s

match a digit, word, or space character, respectively.

\D

,

\W

, and

\S

match anything except a digit, word, or space character, respectively.

[abc]

matches any character between the brackets (such as a, b, or c).

[^abc]

matches any character that isn’t between the brackets.