How can I do a global regular expression match in Perl?


Question

I am trying to come up with a regular expression in Perl matching multiple patterns and returning all of them like preg_match_all in PHP does.

Here's what I have:

$str = 'testdatastring';
if($str =~ /(test|data|string)/) {
        print "its found index location: $0 $-[0]-$+[0]\n";
        print "its found index location: $1 $-[1]-$+[1]\n";
        print "its found index location: $2 $-[2]-$+[2]\n";
        print "its found index location: $3 $-[3]-$+[3]\n";
}

This only gives me the first match which in this is 'test'. I want to be able to match all occurrences of specified patterns: 'test', 'data' and 'string'.

I know that in PHP, you can use preg_match_all for this kind of purpose:

if(preg_match_all('/(test|data|string)/', 'testdatastring', $m)) {
        echo var_export($m, true);
}

The above PHP code would match all 3 strings: 'test', 'data' and 'string'.

I want to know how to do this in Perl. Any help would be greatly appreciated.

1
1
6/4/2009 9:33:43 PM

Accepted Answer

The Perl equivalent to

preg_match_all('/(test|data|string)/', 'testdatastring', $m)

is

@m = ("testdatastring" =~ m/(test|data|string)/g);

The /g flag stands for global, so it returns a list of matches in list context.

11
6/4/2009 9:33:02 PM

See http://www.anaesthetist.com/mnm/perl/regex.htm . Basic syntax (from there) is:

$_ = "alpha xbetay xgammay xdeltay so on";
($first, $second, $third) = /x(.+?)y/g;

Note the /g


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