"Mastering Regular Expressions" Read Note 001

. Match any character except newline characters ( as a matching target when used in [] .)

^ start of matching string : ^cat matches cat,catd.

$ Match end of string : $cat match cat,dddCat

? repeat 0 or one time ( acts only on the front adjacent element ). Colou?r Match Color,colour Col (OU)? r Match Colr,colour

+ Repeat 1 or more times

* Repeat 0 or more times

[] matches any one of the characters in parentheses : c[ae]t matches Cat,cet,ccatd,cetdd,aacat.

- represents a range ( only used in [] , otherwise as a matching target ):[0-9], Match any one number .

^ ( when used in [] ) matches characters not in brackets:t[^2-6] matches t1,t7,t9t, does not match t2,t6d,t34d,123t,t1

A|b match a or b:aa|cc match : aa,cc; (A|CD) 3 matches : 12a3, 12CD3

\< match start ; \> match End

{N,m} Match Duplicates N to the m:ta{1,4}d Match Tad,taad,taaad,taaaad

match the hour of the year

([01]? [0-9]|2[0-4]): [0-5][0-9]

([01]? [4-9]| [012]? [0-3]): [0-5][0-9]

(?:  

) to look around (from left to right to see the text) to indicate   get the front position of the match, such as   get ' ab ' where it appears: Match   match   TADC&NBSP; a (? =ad)   match &NBSP, TAADC&NBSP; TADC

(? <= ...   Positive Reverse view (right-to-left viewing text) indicates the post-location of the matched content, such as (? <= AD); get where ' ab ' appears: Match tad_bc (' _ ' does not exist in the word, it represents the location of the match )

(?! ... ) Negative order Surround

(? <! ... ) negative reverse-order surround

\ t tab

\s Blank

\s any characters except whitespace characters

\w = = [A-za-z0-9]

\w ==[^a-za-z0-9]

\d = = [0-9]

\d ==[^0-9]

"\b" matches the word boundary ( with \s,\n,\t, comma , period as the boundary ) and does not match any characters. The match is just a position where the side of the position is the character that makes up the word, the other side is a non-word character, the start or end position of the string. "\b" is 0 width.

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Modifier

In an expression, such as /a[0-9]/i is a modifier, which indicates that the match ignores case

G Global Match

x loose arrangement

"Mastering Regular Expressions" Read Note 001