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digitalmars.D - array of pointers & assignment

reply "Alexander Panek" <alexander.panek brainsware.org> writes:
Hello,

I`ve got a problem with the assignment of a pointer inside an array of  
pointers:

class A {
	Node[] *Nodes;

	void foo(Node xyz)
	{
		int i = 0;

		Nodes[i] = &xyz;
	}
}

class Node {
	... some data ...
}

Dmd gives me this error:
	xml.d(350): cannot implicitly convert expression (#this.Nodes[i]) of type  
Node * to xml.Node[]

.. and I don`t really get what`s wrong here. "&xyz" should give me the  
address of the object "xyz" , so it should be a pointer, shouldn`t it?

Regards,
Alex
-- 
huh? did you say something? :o
Apr 04 2005
parent reply Tom S <h3r3tic remove.mat.uni.torun.pl> writes:
Alexander Panek wrote:
 Hello,
 
 I`ve got a problem with the assignment of a pointer inside an array of  
 pointers:
 
 class A {
     Node[] *Nodes;
 
 <snip>

In D you'd declare an array of pointers to Node using this syntax: Node*[] nodes; /* http://digitalmars.com/d/arrays.html */ But generally you can get away with: Node[] nodes; And that will be an array of references to Node instances. /* nodes[i] = xyz; won't create a copy of the object but a copy of the reference */
 Dmd gives me this error:
     xml.d(350): cannot implicitly convert expression (#this.Nodes[i]) of 
 type  Node * to xml.Node[]
 
 .. and I don`t really get what`s wrong here. "&xyz" should give me the  
 address of the object "xyz" , so it should be a pointer, shouldn`t it?

Yes, and it is a pointer :) That's what dmd is saying: "(...) cannot implicitly convert expression (#this.Nodes[i]) of type Node * (...)" -- Tomasz Stachowiak /+ a.k.a. h3r3tic +/
Apr 04 2005
parent reply "Alexander Panek" <alexander.panek brainsware.org> writes:
On Mon, 04 Apr 2005 19:00:46 +0200, Tom S  
<h3r3tic remove.mat.uni.torun.pl> wrote:

 Alexander Panek wrote:
 Hello,
  I`ve got a problem with the assignment of a pointer inside an array  
 of  pointers:
  class A {
     Node[] *Nodes;

In D you'd declare an array of pointers to Node using this syntax: Node*[] nodes; /* http://digitalmars.com/d/arrays.html */ But generally you can get away with: Node[] nodes; And that will be an array of references to Node instances. /* nodes[i] = xyz; won't create a copy of the object but a copy of the reference */

That was my concern, to have only references to objects and not copied objects at all. Thanks for your help, gonna try that :). Regards, Alex -- huh? did you say something? :o
Apr 04 2005
parent Mike Parker <aldacron71 yahoo.com> writes:
Alexander Panek wrote:
 On Mon, 04 Apr 2005 19:00:46 +0200, Tom S  
 <h3r3tic remove.mat.uni.torun.pl> wrote:

 That was my concern, to have only references to objects and not copied  
 objects at all.

Just be aware that classes are passed by reference, but structs are passed by value. So you don't need to use pointers for classes, but you would for structs to avoid copying.
Apr 04 2005