my $string = 'abcdefghijk'; 
my %match = (bc => "Michelangelo", efg => "Raffaello",de => "Caravaggio",ijk => "Tintoretto",hij=>"Leonardo",);

foreach $art (keys %match){
    print "this is INDEX $art =>",join(',',$match{$art}),"\n", if index my $tring,$art;
    }

##</code><code>##

Parentheses missing around "my" list at
	C:\Users\Alberto\Documents\NetBeansProjects\PerlProject\Perl Essentials\hash_ref\partial_hash_check.pl line 48 (#1)
    (W parenthesis) You said something like
    
        my $foo, $bar = @_;
    
    when you meant
    
        my ($foo, $bar) = @_;
    
    Remember that "my", "our", "local" and "state" bind tighter than comma.    
Use of uninitialized value $tring in index at
	C:\Users\Alberto\Documents\NetBeansProjects\PerlProject\Perl Essentials\hash_ref\partial_hash_check.pl line 48 (#2)
    (W uninitialized) An undefined value was used as if it were already
    defined.  It was interpreted as a "" or a 0, but maybe it was a mistake.
    To suppress this warning assign a defined value to your variables.
    
    To help you figure out what was undefined, perl will try to tell you
    the name of the variable (if any) that was undefined.  In some cases
    it cannot do this, so it also tells you what operation you used the
    undefined value in.  Note, however, that perl optimizes your program
    and the operation displayed in the warning may not necessarily appear
    literally in your program.  For example, "that $foo" is usually
    optimized into "that " . $foo, and the warning will refer to the
    concatenation (.) operator, even though there is no . in
    your program.
    
this is INDEX efg =>Raffaello
this is INDEX de =>Caravaggio
this is INDEX hij =>Leonardo
this is INDEX bc =>Michelangelo
this is INDEX ijk =>Tintoretto