mrc has asked for the wisdom of the Perl Monks concerning the following question:

In this example: 
if ($string =~ /ab|ac|ad|ba|bla|etc/) {print $1}

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is there a way to find the position of match? In the above example if match will be "ac", position number is 2.

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Re: position number
by toolic (Bishop) on Sep 18, 2013 at 18:37 UTC
    You might want something like: 
    use warnings;
use strict;

my @pats = qw(ab ac ad ba bla etc);
my %pos;
@pos{ @pats } = 1 .. @pats;
my $re = join '|', @pats;
$re = qr/$re/;
while (<DATA>) {
    print "$1 $pos{$1}\n" if /($re)/;
}

__DATA__
fable
fact

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    Output: 

    ab 1
ac 2

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Re: position number
by Happy-the-monk (Canon) on Sep 18, 2013 at 18:12 UTC

    if ($string =~ /ab|ac|ad|ba|bla|etc/) {print $1}

    I guess you meant to write if ($string =~ /(ab|ac|ad|ba|bla|etc)/) {print $1}

    ... with a set of parantheses around what you want to match.

    There's index to tell the position of a substring in a string.

    Cheers, Sören

    Créateur des bugs mobiles - let loose once, run everywhere.
    (hooked on the Perl Programming language)

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Re: position number
by Laurent_R (Canon) on Sep 18, 2013 at 19:06 UTC

    The @- special variable contains the start offset of the match and submatches. Possibly what you are looking for.

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      Requisite link for the OP: @- from perlvar.

      #11929 First ask yourself `How would I do this without a computer?' Then have the computer do it the same way.

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        Yes, this is what I'm looking for. Thanks.
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      TIL:

      my $re = join '|', map "($_)", qw[ab ac ad ba bla etc];

for (qw[tab act mad bar blank fetch]) {
    printf "%-6s %-4s %d\n", $_, $+, $#- if /$re/;
}

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      Output:

      tab    ab   1
act    ac   2
mad    ad   3
bar    ba   4
blank  bla  5
fetch  etc  6

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      Thanks to all specially to Laurent_R and kennethk. The @- is what I'm looking for.
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