my $new_string = testing_string($string); 

    sub testing_string {
        my $content = $_[0]; #string copy, expensive
        # do some stuff
        $content =~ s/a/b/sg;
        return $content; #string copy, expensive
    }

[download]
   # do stuff here
    my %test_var;
    $test_var{$string} = $string; # double!! string copy and hash 
                     # sum calculation, expensive. And why   
                     # this senseless copying into a hash? a scalar 
                     # variable (i.e $string) is global too
    testing_string();
    $string = $test_var{$string}; # string copy and hash sum calculati
+on of $string

    sub testing_string_2 {
        # do some stuff here
        $test_var{$string} =~ s/a/b/sg;  
    }

[download]

What you could do is this:

   testing_string(\$string); #send a reference to $string instead of $
+string

    sub testing_string {
        my $contentref = $_[0];
        # do some stuff
        $$contentref =~ s/a/b/sg;
   }

[download]

But are you sure you have problems with the speed of your script? Did you profile your script to see where it is slow? You might google for "premature optimizations", this is the most common mistake programmers make. And as you can see, often they even make it more expensive because they don't know enough about the underlying mechanism.

Simply copying strings is a very fast operation on modern CPUs because they can use special instructions (maybe even DMA transfers) for it. You might only save micro- or milliseconds if this operation is not done thousand or million times in your script

In reply to Re^3: Whats quicker - passing along as variable to sub, or global var? by jethro
in thread Whats quicker - passing along as variable to sub, or global var? by ultranerds

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