Actually, I think you're OK as is for the moment (but consider the other replies above, as well). Optimization probably won't gain you much for the case in point.

However, consider the case in which you try to deal with multiple "parents:"

#!/usr/bin/perl
use strict;
use warnings;
#829841

my @parent =<DATA>;
my $substring = 'xxx';
my @count;
my $total;
    
for my $parent (@parent) {
    @count = split /$substring/, $parent;
    $total = $#count;
    print "there are $total $substring in $parent\n"; 
    if($parent =~ /$substring[\s\S]*$substring/) {   
        print "Duplicates\n" 
    }
    elsif( $parent !~ /$substring/) { 
        print "None\n"; 
    }
    else { 
        print "Unique\n" 
    }
    print "-"x25 ."\n";
    @count=""; $total=0;
}

__DATA__
xxx xxx xxx
xxx yyy xxx
yyy xxx yyy
zyx zyx
xx
x

[download]

Unless you reset your array and counter, you'll encounter off-by-1 inaccuracies.

Moving on to your actual question: the standard technique is to use a hash (keys are unique and values can provide the counter for each variant element in your "$parent").

The excellent reply by JSchmitz to Count number of words on a web page? provides code; the "Perl Cookbook" (Christiansen & Torkington, O'Reilly) offers alternates and explanations at pp102-103 (at least in my May 1999 edition)

Updated: Took me so long to write this that citing only the first reply above was misleading

In reply to Re: Counting SubStrings, Style Question by ww
in thread Counting SubStrings, Style Question by se@n

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