...
  sub func
 {
  print 'The Command Seperator is: ', $^O =~ /MSWin32/i ? '&' : ';', "\n"
 }

 func();
 func();
 ...

##</code><code>##

  sub func
 {
  print 'The Command Seperator is: ',
         qw(; &)[ $^O =~ /MSWin32/i ],
         "\n"
 }