What are the regular expression operators

This article mainly introduces what the regular expression operators are. It is very detailed and has a certain reference value. Friends who are interested must read it!

Common matching

. (matches any single character. For example, the regular expression r.t matches these strings: rat, rut, r t, but not root)

$(match line Terminator. For example, the regular expression weasel$ can match the end of the string "He's a weasel", but not the string "They are a bunch of weasels.")

^ (matches the beginning of a line. For example, the regular expression ^ When in can match the beginning of the string "When in the course of human events", but not "What and When in the".)

* (matches the 0 or more characters that precede it. For example, the regular expression. * means that any number of characters can be matched.)

\ (this is the reference character used to match the metacharacters listed here as normal characters. For example, the regular expression\ $is used to match the dollar sign, not the end of the line, and similarly, the regular expression\. A wildcard used to match dot characters rather than any character)

[] [c1-c2] [^ c1-c2] (matches any character in parentheses. For example, the regular expression Raou] t matches rat, rot, and rut, but does not match ret. You can use a hyphen-in parentheses to specify an interval of characters, for example, the regular expression [0-9] can match any numeric character; you can also set multiple intervals, such as the regular expression [A-Za-z] can match any uppercase and lowercase letter. Another important use is "exclude". To match characters outside the specified interval-- the so-called complement-- use the ^ character between the parentheses on the left and * characters. For example, the regular expression [^ 269A-Z] will match any character except 2, 6, 9, and all uppercase letters.)

\

(the beginning of the matching word (word). For example, regular expressions\