regex - perl negative lookahead for not matching a word -

regex - perl negative lookahead for not matching a word -

i found regex not match word question regular look match string not containing word? .

u(?!i) match word u not followed i. reply says checks if each character not followed hede. shouldn't regex /^(.(?!hede))*$/. works words containing hede not starting it. why utilize /^((?!hede).)*$/ . whats difference between position of dot. used re=debug couldn't still meaning

(?!hede) means look ahead see if there not: hede. create sense if there other character followed hede hence . after (?!hede) valid regex.

regex explanation of ^((?!hede).)*$

^ origin of string ( grouping , capture \1 (0 or more times): (?! ahead see if there not: hede 'hede' ) end of look-ahead . character except \n )* end of \1 $ before optional \n, , end of string

use (?<! look behind

pattern explanation of ^(.(?<!hede))*$

^ origin of string ( grouping , capture \1 (0 or more times): . character except \n (?<! behind see if there not: hede 'hede' ) end of look-behind )* end of \1 $ before optional \n, , end of string

it's improve explained under lookahead , lookbehind zero-length assertions

they not consume characters in string, assert whether match possible or not

regex perl