A useful feature of regular expressions is the optional use of parentheses. There are numerous reasons to use them, but one is to report parts of the match.<\/p>\n
Consider the following:<\/p>\n
if($strng=~m\/(hehe(_[\\d]+_)([\\d]+d)(-[d]+))\/i){<\/p>\n
print “$1\\n$2\\n$3\\n$4\\n”;<\/p>\n
}
\nelse{<\/p>\n
print “no match”;
\n}<\/p>\n<\/div>\n
The output would be (assuming no typos:)<\/p>\n
$1 denotes the contents of the first set of parentheses in the matching pattern, $2 the second, and so on. The groupings can be used to organize the output from the match.<\/p>\n
Source:<\/p>\n
perldoc.perl.org<\/a><\/p>\n roberts perl tutorial<\/a><\/p>\nJack of Oracle Tutoring by Jack and Diane,<\/a> Campbell River, BC.\n","protected":false},"excerpt":{"rendered":" Self-tutoring about computer science: the tutor mentions using parentheses in Perl regular expressions to form groups. A useful feature of regular expressions is the optional use of parentheses. There are numerous reasons to use them, but one is to report …<\/p>\n