in reply to How to look for exact pattern match

grep doesn't do what you think it does. For a start you're assigning the return value to a scalar, but it returns a list.

I think that what you want is something like this:

my @in = qw(bga cbga test);
my @out;
my @test = qw(bga);

foreach my $test (@test) {
  push @out, grep { /$test/ } @in;
}

[download]

But I'm slightly worried by your phrase "exact pattern match". Perhaps what you really want is:

my @in = qw(bga cbga test);
my @out;
my @test = qw(bga);

foreach my $test (@test) {
  push @out, grep { $_ eq $test } @in;
}

[download]
--
<http://www.dave.org.uk>

"The first rule of Perl club is you don't talk about Perl club."

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Re: Re: How to look for exact pattern match
by juo (Curate) on Oct 30, 2001 at 15:47 UTC

    It's not really what I like to do. I want to remove all exact matches which occur in @test out of the array @in. So the array @in should become (cbga test). With (grep s/($temp)/ /ig,@new_array) it removed all matches instead of exact matches so my array became (c test) instead of (cbga test).

[reply]

      You're not removing the elements, you're replacing them with spaces.

      I think you want this, then:

      my @in = qw(bga cbga test);
my @out = @in;
my @test = qw(bga);

foreach my $test (@test) {
  @out = grep { $_ ne $test } @out;
}

      [download]

      Which leave @out contains all the elements from @in that don't exist in @test.

      Actually, thinking about it, that's the disjunction of two sets and there's probably some really short recipe to do it in the Cookbook.

      --
      <http://www.dave.org.uk>

      "The first rule of Perl club is you don't talk about Perl club."

[reply]
[d/l]
        And since the original poster wanted case insensitivity, remember to sprinkle around lc's or uc's liberally: 
        @out=grep { lc($_) ne lc($test) } @out;

        [download]
        or somesuch drivel.
[reply]
[d/l]

        Actually, thinking about it, that's the disjunction of two sets and there's probably some really short recipe to do it in the Cookbook.

        ITYM FAQ, but yes. 

        $ perldoc -q 'difference'
Found in /usr/lib/perl5/5.6.1/pod/perlfaq4.pod
       How do I compute the difference of two arrays?  How do I
       compute the intersection of two arrays?
...

        [download]
[reply]
[d/l]

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