True at word boundary. /B No True when not at word boundary. /cX Yes Match the control character Control-X (/cZ, /c[, etc.). /C Yes Match one byte (C char) even in utf8 (dangerous). /d Yes Match any digit character. /D Yes Match any nondigit character. /e...
Theword-boundaryanchor\bmatches at either end of a word. #!/usr/bin/perlusewarnings; $_ ='neofred';if(/fred\b/) {print"match\n"; } It matches, but with,/\bfred\b/, it doesn't match. \w \wanchor matches ordinary letters, digits, and underscores. It identical to[0-9a-zA-Z...
I also use the word boundary anchors \b because I don’t want to match in the middle of other words, such as “BioPerl” or “PerlPoint”: #!/usr/bin/perl # not-perl6.pl print "Trying negated character class:\n"; while( <> ) { print if /\bPerl[^6]\b/; # } I’ll ...
We can use the combination of regmatches and gregexpr in R so see the letters this regex is matching. Then do a global sub (replace all the matches, not just the first) with the \\Uppercase version of the \\1st group. ## positive look-behind assertion for a word boundary ## then...
^ only matches at the beginning of the string $ only matches at the end of the string ^^ matches at the beginning of any line within the string $$ matches at the end of any line within the string << A word boundary, but only matches the transition from non-word chara...
\b word boundary \B not a word boundary ^ start of subject also after an internal newline in multiline mode (after any newline if PCRE2_ALT_CIRCUMFLEX is set) \A start of subject $ end of subject also before newline at end of subject also before internal newline in multiline mode ...
\b Match word boundary (between \w and \W) \B Match except at word boundary (between \w and \w or \W and \W) \A Match string start (regardless of /m) \Z Match string end (before optional newline) \z Match absolute string end ...
\bMatchwordboundary \BMatchnon-wordboundary RepetitionFactors (greedy,matchasmanytimesaspossible) CharacterBehavior *Match0ormoretimes +Match1ormoretimes ?Match1or0times {n}Matchexactlyntimes {n,}Matchatleastntimes {n,m}Matchatleastnbutnotmorethanm ...
\Bmatches when not at a word boundary \Amatches at the start of the subject \Zmatches at the end of the subject, also matches before a newline at the end of the subject \zmatches only at the end of the subject \Gmatches at the first matching position in...
This incorrectly matches because there is no word boundary in the middle of “cocoa”: $ sed --version sed(GNU sed)4.8 $ echo'cocoa'| sed -nE'/(\bco){2}/p'cocoa Without the quantifier, there’s no problem and no matches: