Classes
The rules change if your you're in a character class or not.
#!/bin/perl -l
=begin
The rules change if your you're in a character class or not
Star (*) is never a metacharacter within a class, while
dash (-) usually is
A character class must always match a character to be successful
A negated class must still match a character, but one not listed
Dot (.) ussualy does not match a newline,
while a negated class like [^*] ussualy does
=cut
$a = "Is star * a metacharacter?";
$b = "star * is a metacharacter";
$c = "star * is a metacharacter!";
$d = "This is a 'quote \n on two' lines";
print ($a =~ m/([a-z *])+/); # r
print ($b =~ m/[A-Z]+/); #
print ($c =~ m/([^a-z *])+/); # !
print ($d =~ m/'(.*)'/); #
print ($d =~ m/'([^']*)'/); # $1 = quote, $2 = on two
POSIX
POSIX expressions are a special kind of character classes.
#!/bin/perl -l
=begin
POSIX bracket expressions are a special kind of character classes
They use the same syntax with square brackets
An example is [:lower:], which represents any lower-case letter
(within the current locale)
It is comparable with [a-z], but includes other characters such as ñ or õ
[:alnum:] alphabetic characters and numeric character
[:alpha:] alphabetic characters
[:lower:] lowercase alphabetics
[:upper:] uppercase alphabetics
=cut
$a = "This is a 123 string õ";
print ($a =~ m/([[:alnum:]]+)/); # This
print ($a =~ m/([[:alnum:]]+)/g); # Thisisa123string
Last update: 186 days ago
