use strict;
my $str = '2
-
20
20a
201
2018
2018-
2018-0
2018-02
2018-02-
2018-02-1
2018-02-1@
2018-02-12
2018-02-12
2018-02-12 0
2018-02-12 00
2018@02-12 00:
2018-02-12 00:
2018-02-12 00:5
2018-02-12 00:55
2018-02-12 00:55:
2018-02-12 00:55:2
2018-02-12 00:55:2z
2018-02-12 00:55:22';
my $regex = qr/^
(?:
\d{1,4}|
\d{4}-|
\d{4}-[01]|
\d{4}-(?:0[1-9]|1[0-2])|
\d{4}-(?:0[1-9]|1[0-2])-|
\d{4}-(?:0[1-9]|1[0-2])-[0-3]|
\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[0-1])|
\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[0-1])\s|
\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[0-1])\s[0-2]|
\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[0-1])\s(?:2[0-3]|[01]\d)|
\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[0-1])\s(?:2[0-3]|[01]\d):|
\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[0-1])\s(?:2[0-3]|[01]\d):[0-5]|
\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[0-1])\s(?:2[0-3]|[01]\d):[0-5]\d|
\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[0-1])\s(?:2[0-3]|[01]\d):[0-5]\d:|
\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[0-1])\s(?:2[0-3]|[01]\d):[0-5]\d:[0-5]|
\d{4}-(?:0[1-9]|1[0-2])-(?:0[1-9]|[12]\d|3[0-1])\s(?:2[0-3]|[01]\d):[0-5]\d:[0-5]\d
)
$/mxp;
if ( $str =~ /$regex/g ) {
print "Whole match is ${^MATCH} and its start/end positions can be obtained via \$-[0] and \$+[0]\n";
# print "Capture Group 1 is $1 and its start/end positions can be obtained via \$-[1] and \$+[1]\n";
# print "Capture Group 2 is $2 ... and so on\n";
}
# ${^POSTMATCH} and ${^PREMATCH} are also available with the use of '/p'
# Named capture groups can be called via $+{name}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Perl, please visit: http://perldoc.perl.org/perlre.html