sub test1 { ++$_[0] ; print "T1 [@_]\n" ; test2($_[0]) ; } sub test2 { ++$_[0] ; print "T2 [@_]\n" ; test3($_[0]) ; } sub test3 { ++$_[0] ; print "T3 [@_]\n" ; print "end\n" ; } my $n = 10 ; test1($n) ; print "N: $n\n" ;