Question

Forgive me for the (probably) stupid question, but I’m messing around with this code (actually a model of something in a larger program), and something is throwing me off:

sub recurse { 
  my $m = shift; 
  $g .= "::" . $m; 
  if ($m == 0) { return $g; } 
  else { $m--; recurse ($m); }
}

for ($i = 0; $i < 3; $i++)
{
  my $g = '';
  $str = recurse (10); 
  print $str . "\n";
}

The first iteration of the ‘for’ loop works fine. On subsequent iterations, however, I am having an issue. As you can see, the global variable $g is reset first thing in the ‘for’ loop before the recursive function is called. With the debugger, I can see that $g is set back to ” before the function is called. However, as soon as the function ‘recurse’ is entered, it goes back to the previous value. What am I missing here?

As a corollary, I don’t like using a global variable here. What is the ‘correct’ way to do it without making $g a parameter for recurse()?

Answer 1

my $g is a local variable so it’s not the same one you use inside recurse. Removing my will fix that, though it’s still going to be an ugly code.

You can pass $g a second parameter to the resurse function.

Note: use strict; is your friend 😉