use strict;

my $string = 'bar a2 b2 c3 d3 d4 a1 f2 f3';
my $flag = 0;

foreach(split(/\s+/, $string)) {
   $flag++, last if /\w\d/;
}
print "foo's found in list\n" if $flag;

##</code><code>##

use strict;

my @foos = qw(d4 b2);
my $string = 'bar a2 b2 c3 d3 d4 a1 f2 f3';
my $flag = 0;

foreach my $cand (split(/\s+/, $string)) {
   foreach(@foos) {
       $flag++, last if $cand =~ /$_/;
   }
}
print "foo's found in list\n" if $flag;