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Perl Programming
Handling Arguments
  • Two common means of passing arguments to subs
    • Pass by value
    • Pass by reference
    • Perl allows either
  • Arguments are passed into the @_ array
    • @_ is the "fill in the blanks" array
    • Usually should copy @_ into local variables

        sub add_one {           # Like pass by value
            my ($n) = @_;       # Copy first argument
            return ($n + 1);    # Return 1 more than argument 
        }

        sub plus_plus {         # Like pass by reference
            $_[0] = $_[0] + 1;  # Modify first argument
        }

        my ($a, $b) = (10, 0);

        add_one($a);            # Return value is lost, nothing changes
        $b = add_one($a);       # $a is 10, $b is 11

        plus_plus($a);          # Return value lost, but a now is 11
        $b = plus_plus($a);     # $a and $b are 12
      
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