The only thing I'd add to what mr_mischief and ikegami have said, is that it can be useful to use __DATA__ to set up some test data before your loop and then test to see that your loop does what you want it to, as so:

#!/usr/bin/perl 
use warnings;
use strict;
#
# Using __DATA__ to test a loop.
#
my $string = 'test'; 
my $inputs = 'test.txt'; 
# open(my $table, "<", $inputs) or die "can't open $inputs.\n"; 
# while (<$table>) { 
while (<DATA>) { 
    print if ( m/\Q$string\E/o );
} 
# close($table); 
__DATA__
test
tst
foo bar test
This is a test
This is something else.
[download]

The output is:

C:\Code>perl match.pl
test
foo bar test
This is a test
[download]