Hi everyone:
I wrote a sample script and want to see how call-by-value
works.
my understanding is that once variable is be localized by my
function,
a copy of the value of argument is being send to
function/subroutine.
Here is my sample script:
use strict;
use warnings;
sub addition
{
#$_<0> = $_<0> + 1;
$a = $a + 1;
print "in subroutine $a value changed to: $an";
}
my $a = 5;
&addition($a);
print "after subroutine the value of $a is: ",
$a;
I tried two options
a) I used  _ arrary to access argument and increment it by 1.
the
result is that value of '$a' changed in main block as well.
b) I used $a = $a + 1 in subroutine, the output is
"Use of uninitialized value in addition (+) at
C:CIS068Echap10call_by_value.pl line 12.
in subroutine $a value changed to: 1
after subroutine the value of $a is: 5 " I am sure if
option b)
demonstrated purpose of call-by-value.
Plase give me some suggestion on why a) didn't work,
wheather b) is a right approach to demonstrate the purpose
of
call-by-value. Thanks!
Jeff
3-12-07
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