?

:)

4

, . , . " " - , regex regexp. , , , .

regex

, , - , . , , , . , , :

:

  • john_doe;
  • jo-hn_doe;
  • john12_as.

, , Jo, .

, , . , "The" "t", "h", "e".

  • "the" => The fat cat sat onthemat.

, , . , . :

.

, .

[ ]

, .

[^ ]

Negated character class. Matches any character that is not contained between the square brackets

*

0 .

+

1 .

?

.

{n,m}

"n", "m" .

(xyz)

.

|

.

\

. [ ] ( ) { } . * + ? ^ $ \ |

^

.

$

.

, . :

.

,

\w

- :[a-zA-Z0-9_]

\W

- :[^\w]

\d

: [0-9]

\D

: [^\d]

\s

: [\t\n\f\r\p{Z}]

\S

: [^\s]
Look Around

Look Around , , . , , , .

?=

Lookahead

?!

Lookahead

?<=

Lookbehind

?

Lookbehind

, . .

i

: .

g

: .

m

: .
vs.

"" , .

  • "/(.*at)/" => The fat cat sat on the mat.

"" , ?. .

  • "/(.*?at)/" => The fat cat sat on the mat.

?

: