Re: How to look for exact pattern match

[davorg]

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;
}

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;
}

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

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

[juo]

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).

[davorg]

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;
}

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."

[Fletch]

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?
...

[clintp]

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;

or somesuch drivel.