Computer science: Perl regex: grouping with parentheses
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 parts of the match.
Consider the following:
$strng=”Hehe_12345_68d-910″;
if($strng=~m/(hehe(_[\d]+_)([\d]+d)(-[d]+))/i){
print “$1\n$2\n$3\n$4\n”;
}
else{
print “no match”;
}
The output would be (assuming no typos:)
Hehe_12345_68d-910
_12345_
68d
-910
_12345_
68d
-910
$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.
Source:
Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.
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