#!/usr/cs/bin/perl
#
# File: ref.pl  --- demonstrates pass-by-reference to subroutines.
#
############################## integers ############################

$a = 1;
$b = 1;
&Inc1 ($a);
&Inc2 (\$b);
print "a = $a, b = $b\n";

sub Inc1 {      # doesn't work
  ($x) = @_;
  $x++;
}

sub Inc2 {      # works         
  (*x) = @_;
  $x++;
}

############################## strings #############################

$name1 = "James";
$name2 = "French";
&Stretch1 ($name1);
&Stretch2 (\$name2);
print "name1 = $name1, name2 = $name2\n";

sub Stretch1 {       # doesn't work
  ($str) = @_;    
  $str =~ s/./$& /g;
}

sub Stretch2 {       # works
  (*str) = @_;    
  $str =~ s/./$& /g;
}

######################### multiple arrays ##########################

@array1 = (1, 2, 3);
@array2 = (4, 5, 6);
(*array3, *array4) = SwapArrays (\@array1, \@array2);
print "array1 = (", @array1, "), array2 = (", @array2, ")\n";
print "array3 = (", @array3, "), array4 = (", @array4, ")\n";

sub SwapArrays {       # works
  (*a1, *a2) = @_;
  return (\@a2, \@a1);  
}

####################################################################
#
# The results of running this program are:
#
# a = 1, b = 2
# name1 = James, name2 = F r e n c h 
# array1 = (123), array2 = (456)
# array3 = (456), array4 = (123)
# 
####################################################################