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Posted by Jerry Stuckle on 09/28/07 11:42
Summercool wrote:
> so many places, including the book PHP in a Nutshell, p. 80, it says:
>
> $a =& $b # set $a to reference $b
>
> if $a reference $b, then while you can say $b =1, you can't really
> say $a = 1. you need to say *($a) = 1 as in C or C++. Referencing
> must be coupled with dereferencing, and PHP is not doing the
> dereferencing, so why is it call referencing in the first place?
> (don't tell me PHP automatically dereference... as it will be really
> weird).
>
Incorrect. C does not have references. It has pointers only. C++ has
references and you can say a=1 - just like you can say $a=1 in PHP.
Just remember in C++ there is a huge difference between
int & ra = b;
// and
int * pa;
pa = &b;
ra is a reference. pa is a pointer. ra is used *exactly* like b - pa
must be dereferenced.
> and i think in the PHP group, people say "reference" to mean "alias".
>
As they do in C++ and Java, amongst other languages.
> So my questions are
>
> 1) If it is by reference, why don't you need to dereference it as
> mentioned above?
>
Because you don't dereference in C++, either.
> 2) There are actually two "reference" methods (as in my previous post
> topic). One is $obj1 = $obj2, and it works the same as in Java,
> Python, and Ruby (maybe in Perl too?). The other behavior is the $a
> =& $b and it is different, and why is it still called "reference"?
> Why having two different behaviors use the same name which is
> "reference"? Why not call $a =& $b aliasing, and call $obj1 = $obj2
> copying the reference? ($obj2 reference an object, and so copy this
> reference to $obj2)
>
They work the same. $a = &$b says to have $a reference $b instead of
making a copy of $b. This is done automatically in PHP 5 for object
(only). But they are the same.
> In a way, if C, C++, Java, Python, Ruby, all use the word reference to
> mean $obj1 = $obj2, if PHP wants to be different and call "aliase" as
> "reference", and different from the rest of the world, I can respect
> that. But the thing is, why call it reference and then have the other
> behavior $obj1 = $obj2 which is different, and AGAIN call it reference?
>
Again, C does not have references. And PHP works exactly the same as
C++, Java, etc. references.
--
==================
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Jerry Stuckle
JDS Computer Training Corp.
jstucklex@attglobal.net
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