#!perl -w
use strict;
use subs qw/print_log/;

my $var = "Hallo Welt!\n";
print_log $var;

sub print_log
{
   my $string = shift;
   my $logfile = "c:\\temp\\test.log";
   $! = 0;
   unless(open(LOG, ">>", $logfile))
   {
      print "Konnte Logfile nicht oeffnen: $!";
      exit 1;   
   }
   print $string;
   print LOG $string;
   close(LOG);
}