... use quotemeta ...

... or  \Q$string\E its interpolative equivalent:

c:\@Work\Perl\monks>perl -wMstrict -le
"my @inputData = qw(test.dat  test.exe  testadat.exe  testaexe.dat);
 ;;
 my @search_strings = qw(test.dat  test.exe);
 ;;
 print '----- With quotemeta ------------------';
 foreach my $search (@search_strings) {
   print qq{Using search string '\Q$search\E':};
   foreach my $inputLine (@inputData) {
     if ($inputLine =~ m{ \Q$search\E }xms) {
       print qq{  Matched: '$inputLine'};
       }
     }
   }
"
----- With quotemeta ------------------
Using search string 'test\.dat':
  Matched: 'test.dat'
Using search string 'test\.exe':
  Matched: 'test.exe'
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