Perl's references are more than just C pointers. Perl reference counts objects so the reference object that holds onto the 'address' of another object is more like a C++ smart pointer with a whole world of semantics hidden under a fairly conventional looking syntax. Most of the time you needn't worry about the extra semantics, it just works. Occasionally you run into memory leaks with interesting structures that contain reference loops that have to be forcibly broken before the Perl can dispose of the object.

You can't do that in Perl. You cannot stuff an integer in a reference and have Perl retrieve what's in that memory address. And while you can add something to a reference, the result is a number - not a reference. You cannot dereference the result of the addition.

IMO, saying that "Perl references" and "C pointer" are kind of the same is only useful if you know enough Perl and C to know the differences.

Thanks for explaining clearly with example

What 'C' doesn't know is: how many of those "things" exist, but Perl does know. A Perl reference points to a "Perl thing" like: a hash table or an array or a scalar or even a Perl reference to one of these things.

Unlike 'C', a Perl "thing" knows how big it is.

The most common error in 'C' is "off by one" array indicies. Perl helps a lot with these iterators. For example: foreach my $x(@some_array). I don't need to know how big @some_array is, I will get an x for every value in @some_array. In 'C', I have to know explictly how "big it is" or have some other way of finding out (like a signal value in that array).

Hi Monks, Thanks to you all for sharing your knowledge with me. sir_com

For the most part, they act the same. Probably the biggest difference I have noticed is that you don't have to worry about dereferencing a reference after the object referred to goes out of scope:

my $ref;
{
    my $var = 5;
    $ref = \$var;
}

# prints 5
print $$ref;
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1. subroutine references.
2. typeglob references.
3. references to lists (distinct from references to arrays).
4. IO references.
5. LVALUE references.

one distinguishing feature of Perl, not available in C involves DYNAMIC creation of data structures and prevents excessive typing, this feature is called Autovivification, in reference view, a reference springs to existence if it is dereferenced under the assumption that it exists. With this in mind, you would notice that Perl references and C pointers are not exactly the same.

EXAMPLE: (Note the reference is held in the scalar value $reference!)
$$reference=5;           #Dereferencing before creating a reference.
print "$$reference\n";   #Creation of $reference autovivifically.
print "$reference\n";
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