Providing some code is a good start, but please try to write something that compiles (if you did manage to compile your code, this means you didn't actually use strict). What you are looking for is the index function (although a regex would also work, but index is easier to use and understand).

if (-1 != index $str, $key)
{
  # Do something
}
[download]

Using grep, will result in shorter code.

What you've done in your code is create an array with each element only one character in length, so when you use ~~ smartmatch against the array, you're only testing against a substring of a single character.

If I understand what you're attempting to do, this code may help get you on your way:

#!/usr/bin/perl
use warnings;
use strict;

my $str = 'abcdefghijkl';
my %match = (ab => 0, abcd => 0, xyz => 0,);

for my $key (keys %match){
    if ($str =~ /$key/){
        $match{$key}++;
    }
    else {
        print "$key not found in $str\n";
    }
}

for my $k (keys %match){
    print "key: $k value: $match{$k}\n";
}
[download]

-stevieb

I need help understanding a warning I got and correct my syntax on the ~~ operator match.

Also, I appreciate any commnents on the code and method(improving, provide possible oversight on code, etc..)

Again, I am learning so much with all of your help and advice

find myself liking Perl...today ;-)

question 1 I don't understand why on INDEX, the warning says $string is undef? and I also had to declare it again as "my" when I did on pragma.

question 2 whys is the '~~" operator method it's not working

use strict;
use warnings;
use diagnostics;


my @char;
my $art;
my $string = 'abcdefghijk'; 
my %match = (bc => "Michelangelo", efg => "Raffaello",de => "Caravaggi
+o",ijk => "Tintoretto",hij=>"Leonardo",);

@char = split //,$string;


#check that the substring is in hash; 
foreach $art (keys %match){
  if ($string=~/$art/){
      print "There's a match in the string to $art =>", $match{$art}++
+,"\n";
      }    
    }

 #now using GREP
 
 foreach $art (keys %match){
     if (my $seen= grep {$string =~ $art}$match{$art}) 
     {
         print "I have seen using GREP $art=>",$match{$art},"\n"; 
     
     }
 }

#using ~~ match operator

foreach $art (keys %match){
print "this is \~~ $art=> ",join('',$match{$art}) if /$string/i ~~$art
+;    
    }

#using INDEX()

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

"question 1 I don't understand why on INDEX, the warning says $string is undef? and I also had to declare it again as "my" when I did on pragma."

When you get a error (or warning), it's vitally important that you paste it verbatim, not just type in a vague facsimile of the message.

I strongly suspect that the error you got didn't mention $string at all; instead, it made reference to $tring! (Note the missing 's'.)

So, to fix, add the 's' and remove the my (which you added).

"question 2 whys is the '~~" operator method it's not working"

That's the smart-match operator. It's experimental and subject to change. I recommend you learn non-experimental Perl before delving into ~~.

-- Ken

thank you

I will add the error message it returns next time....Idon't know how my eyes missed that "s"...I spent time so much time trying to understand the error before asking. but ,now that you've pointed it out , I can see it clearly on the error message

Use of uninitialized value $tring in index at
    C:\Users\Alberto\Documents\NetBeansProjects\PerlProject\Perl Essen
+tials\hash_ref\partial_hash_check.pl line 49 (#3
[download]

yeap, message said it was experimental too but I didn't actually understood that it may nt work...WILL stick with your advice.

grazie

Now, I have a question on WHY index worked at all? yes, I got an error while typing $string variable(skipped the "s" in code). however, I got an output anyways?

so i went back and replicated the error so you can see it..again

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

foreach $art (keys %match){
    print "this is INDEX $art =>",join(',',$match{$art}),"\n", if inde
+x my $tring,$art;
    }
[download]

Parentheses missing around "my" list at
    C:\Users\Alberto\Documents\NetBeansProjects\PerlProject\Perl Essen
+tials\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 c
+omma.    
Use of uninitialized value $tring in index at
    C:\Users\Alberto\Documents\NetBeansProjects\PerlProject\Perl Essen
+tials\hash_ref\partial_hash_check.pl line 48 (#2)
    (W uninitialized) An undefined value was used as if it were alread
+y
    defined.  It was interpreted as a "" or a 0, but maybe it was a mi
+stake.
    To suppress this warning assign a defined value to your variables.
    
    To help you figure out what was undefined, perl will try to tell y
+ou
    the name of the variable (if any) that was undefined.  In some cas
+es
    it cannot do this, so it also tells you what operation you used th
+e
    undefined value in.  Note, however, that perl optimizes your progr
+am
    and the operation displayed in the warning may not necessarily app
+ear
    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
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