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c#pointers
Pyr0lle
Pyr0lle

Reputation: 80

Cannot take the address of, get the size of, or declare a pointer ro a managed type

I'm trying to implement a double linked list in c# but I've never used pointers before and cannot find a solution. I'm trying to create the node class which will hold a single item and pointers to the adjacent nodes.

// single elements in the list 
unsafe class Node { Node* previous}
{
    public int data;
    public Node *next;
    public Node *prev = *previous;
}

I keep getting the error in the title and I don't know how to fix it.

Upvotes: 2

Views: 114

Answers (2)

Edney Holder
Edney Holder

Reputation: 1228

As CrowCoder stated you do not and should not use pointers in C# for this implementation. This code should get you started:

internal class LLNode {  
    internal int data;  
    internal LLNode prev;  
    internal LLNode next;  
    public LLNode (int d) {  
        data = d;  
        prev = null;  
        next = null;  
    }  
}

Upvotes: 0

Marc Gravell
Marc Gravell

Reputation: 1063569

You don't need unasnaged pointers or unsafe here at all. Because Node is a class, when you use Node as a parameter, field, variable etc - this is a reference to a Node instance. A reference here means "managed pointer" - i.e. like a pointer, but with full GC support and type safety, etc. So all you need is Node:

class Node
{
    public int Data {get;set;}
    public Node Next {get;set;}     // Next/Previous might want "private set" if
    public Node Previous {get;set;} // you are going to change them via methods
}

More specifically, you cannot readily take an unmanaged pointer to a class in C# - a Node* - that simply isn't a thing you can do. You can do that with struct, but: you almost certainly shouldn't. I expect the point here is to use managed pointers, aka references, i.e. Node, not Node*.

Upvotes: 3

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