Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask
 
PerlMonks  

Re: Dereferencing and comment from Camel

by pg (Canon)
on Dec 21, 2002 at 05:26 UTC ( #221574=note: print w/ replies, xml ) Need Help??


in reply to Dereferencing and comment from Camel

You are 80% right, but it means more than $, you should also include @, %, &.

That is actually sort of comment for a person who is familiar with c/c++. In c/c++, there is a single de-ref operator *. It doesn't matter what the pointer points to, you can always use * to de-ref it.

However in Perl, we do not have such a single operator for de-ref. We have to use @, %, &. There is a big difference. In Perl, in order to de-ref a ref, you have to first know what the ref refs to. In c/c++, type doesn't matter at all, you can always cast a pointer to a certain type, which may have nothing to do with the original type, and then de-ref it, as long as don't corrupt the memory boundary. (In real life, you almost always deref a pointer to something meaningful in the context)
In Perl, if you do:

%a = (1,1,2,2); $a = \%a; print $$a;
It gives you an error, and says that $a is not a SCALAR ref. You have to do:
%a = (1,1,2,2); $a = \%a; print %{$a};
In c/c++, * also de-ref's pointers to functions, in Perl, we have to use &:
sub a { print "abc"; } $a = \&a; &{$a}; # call a, and prints abc


Comment on Re: Dereferencing and comment from Camel
Select or Download Code

Log In?
Username:
Password:

What's my password?
Create A New User
Node Status?
node history
Node Type: note [id://221574]
help
Chatterbox?
and the web crawler heard nothing...

How do I use this? | Other CB clients
Other Users?
Others making s'mores by the fire in the courtyard of the Monastery: (16)
As of 2015-07-29 15:16 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    The top three priorities of my open tasks are (in descending order of likelihood to be worked on) ...









    Results (263 votes), past polls