Perl Regular Expression Cheat Sheet
Regular Expressions can be tricky, that’s why it is a good idea to keep a quick “cheat sheet” handy when working with them, here’s a concise cheat sheet to get you started:
. Match any character \a Match alarm \d Match digit character \D Match non-digit character \e Match escape \f Match form-feed \n Match newline \r Match return \s Match whitespace character \S Match non-whitespace character \t Match tab \w Match "word" character (alphanumeric and "_") \W Match non-word character \022 Match octal char (i.e. 22 octal) \xff Match hex char (i.e. ff in hex) * Match 0 or more times + Match 1 or more times ? Match 1 or 0 times {n} Match exactly n times {n,} Match at least n times {n,m} Match at least n but not more than m times ^ Match if at beginning $ Match if at end Examples: \d{2}-\d{2}-\d{2} # match date in dd-mm-yy format ^[ \t]+ #match leading whitespace [ \t]+$ #match trailing whitespace ^[ \t]+|[ \t]+$ #match leading or trailing whitespace $string =~ m/text/; #returns true if $string contains text, case sensitive $string =~ m/text$/i; #returns true if $string contains text $string =~ s/text1/text/; #replace text1 with text2 in $string $string !~ m/text/; #returns false if $string contains text, case sensitive $string !~ m/text/i; #returns false if $string contains text |
I find it useful to print it out and have it handy whenever I wade into the murky waters of regular expressions.
